#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ull mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const int MOD = 1e9 + 7;
struct Modular{
int x;
Modular(int _x = 0){
x = _x % MOD;
if (x < 0) x += MOD;
}
Modular& operator += (Modular y){
x += y.x;
if (x >= MOD) x -= MOD;
return *this;
}
Modular operator + (Modular y) {
Modular tmp = *this;
return tmp += y;
}
Modular& operator -= (Modular y){
x -= y.x;
if (x < 0) x += MOD;
return *this;
}
Modular operator - (Modular y) {
Modular tmp = *this;
return tmp -= y;
}
// use at your own risk
bool operator == (Modular y){
return x == y.x;
}
bool operator != (Modular y){
return x != y.x;
}
};
ostream& operator << (ostream& out, Modular x){
out << x.x;
return out;
}
const int N = 1e5 + 69, BLOCK = 330;
Modular wow[N][BLOCK];
void solve(){
int n; cin >> n;
vector<int> d(n+1), x(n+1);
for(int i = 1; i <= n; ++i) cin >> d[i] >> x[i];
vector<Modular> dp(n+1);
dp[1] = 1;
Modular ans = 0;
for(int i = 1; i <= n; ++i){
for(int j = 1; j < BLOCK; ++j){
if (i >= j) wow[i][j] += wow[i-j][j];
dp[i] += wow[i][j];
}
ans += dp[i];
if (d[i] == 0) continue;
if (d[i] >= BLOCK){
for(int j = 1; j <= x[i]; ++j){
int p = i + j * d[i];
if (p > n) break;
dp[p] += dp[i];
}
}
else{
if (i + d[i] > n) continue;
int l = i + d[i];
int r = i + min((n - i) / d[i], x[i]) * d[i];
wow[l][d[i]] += dp[i];
if (r + d[i] <= n)
wow[r+d[i]][d[i]] -= dp[i];
}
}
cout << ans << "\n";
}
int main(void){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
solve();
return 0;
}
