/*************************************
* author: marvinthang *
* created: 05.05.2024 17:14:38 *
*************************************/
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i-- > 0; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
const int MOD = 1e9 + 7;
namespace MODULAR {
inline void fasterLLDivMod(unsigned long long x, unsigned y, unsigned &out_d, unsigned &out_m) {
unsigned xh = (unsigned)(x >> 32), xl = (unsigned)x, d, m;
#ifdef __GNUC__
asm(
"divl %4 \n\t"
: "=a" (d), "=d" (m)
: "d" (xh), "a" (xl), "r" (y)
);
#else
__asm {
mov edx, dword ptr[xh];
mov eax, dword ptr[xl];
div dword ptr[y];
mov dword ptr[d], eax;
mov dword ptr[m], edx;
};
#endif
out_d = d; out_m = m;
}
template <class T> T invGeneral(T a, T b) {
a %= b;
if (!a) return b == 1 ? 0 : -1;
T x = invGeneral(b, a);
return x == -1 ? -1 : ((1 - 1LL * b * x) / a + b) % b;
}
template <int MOD> struct ModInt {
unsigned int val;
ModInt(void): val(0) {}
ModInt(const long long &x) { *this = x; }
ModInt & normalize(const unsigned int &v) {
val = v >= MOD ? v - MOD : v;
return *this;
}
bool operator ! (void) { return !val; }
ModInt & operator = (const ModInt &x) { val = x.val; return *this; }
ModInt & operator = (const long long &x) { return normalize(x % MOD + MOD); }
ModInt operator - (void) { return ModInt(MOD - val); }
ModInt & operator += (const ModInt &other) { return normalize(val + other.val); }
ModInt & operator -= (const ModInt &other) { return normalize(val + MOD - other.val); }
ModInt & operator /= (const ModInt &other) { return *this *= other.inv(); }
ModInt & operator *= (const ModInt &other) {
unsigned dummy;
fasterLLDivMod((unsigned long long) val * other.val, MOD, dummy, val);
return *this;
}
ModInt operator + (const ModInt &other) const { return ModInt(*this) += other; }
ModInt operator - (const ModInt &other) const { return ModInt(*this) -= other; }
ModInt operator * (const ModInt &other) const { return ModInt(*this) *= other; }
ModInt operator / (const ModInt &other) const { return ModInt(*this) /= other; }
ModInt pow(long long n) const {
assert(n >= 0);
ModInt res = 1, a = *this;
for (; n; n >>= 1, a *= a) if (n & 1) res *= a;
return res;
}
ModInt inv(void) const {
int i = invGeneral((int) val, MOD);
assert(~i);
return i;
}
ModInt & operator ++ (void) { return *this += 1; }
ModInt & operator -- (void) { return *this -= 1; }
ModInt operator ++ (int) { ModInt old = *this; operator ++(); return old; }
ModInt operator -- (int) { ModInt old = *this; operator --(); return old; }
friend ModInt operator + (const long long &x, const ModInt &y) { return ModInt(x) + y; }
friend ModInt operator - (const long long &x, const ModInt &y) { return ModInt(x) - y; }
friend ModInt operator * (const long long &x, const ModInt &y) { return ModInt(x) * y; }
friend ModInt operator / (const long long &x, const ModInt &y) { return ModInt(x) / y; }
friend ostream & operator << (ostream &out, const ModInt &x) { return out << x.val; }
friend istream & operator >> (istream &in, ModInt &x) { long long a; in >> a; x = a; return in; }
explicit operator bool(void) const { return val; }
explicit operator int(void) const { return val; }
};
using Modular = ModInt <MOD>;
}
using namespace MODULAR;
// end of template
const int BLOCK_SIZE = 320;
void process(void) {
int n; cin >> n;
vector <int> d(n), x(n);
REP(i, n) cin >> d[i] >> x[i];
vector <Modular> dp(n, 1);
int num_bl = (n - 1) / BLOCK_SIZE + 1;
vector <vector <Modular>> sum(num_bl, vector<Modular>(BLOCK_SIZE * (BLOCK_SIZE - 1) / 2));
vector <int> left(num_bl), right(num_bl);
REP(i, num_bl) {
left[i] = i * BLOCK_SIZE;
right[i] = min(n, left[i] + BLOCK_SIZE);
}
auto calc = [&] (int bl, int d, int md, int &k) {
int id = d * (d - 1) / 2 + md;
int st = (left[bl] - md + d - 1) / d * d + md;
if (st >= right[bl]) return Modular(0);
int cnt = (right[bl] - st - 1) / d + 1;
if (k >= cnt) {
k -= cnt;
if (!sum[bl][id]) {
int x = 0;
for (int i = st; i < right[bl]; i += d) {
++x;
sum[bl][id] += dp[i];
}
}
return sum[bl][id];
}
Modular res = 0;
while (k--) {
res += dp[st];
st += d;
}
k = 0;
return res;
};
REPD(i, n) if (d[i]) {
if (d[i] >= BLOCK_SIZE) {
FORE(j, 1, x[i]) {
int k = i + d[i] * j;
if (k >= n) break;
dp[i] += dp[k];
}
} else {
int bl = i / BLOCK_SIZE;
for (int j = i + d[i]; x[i]-- && j < right[bl]; j += d[i]) {
dp[i] += dp[j];
}
++x[i];
int v = i % d[i];
while (x[i] && ++bl < num_bl) {
dp[i] += calc(bl, d[i], v, x[i]);
}
}
}
cout << dp[0] << '\n';
}
int main(void) {
ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
file("trains");
// int t; cin >> t; while (t--)
process();
// cerr << "Time elapsed: " << TIME << " s.\n";
return (0^0);
}
