#include <bits/stdc++.h>
using namespace std;
using lint = long long;
const int MOD = 1000000007;
struct mint {
int val;
mint() : val(0) {}
mint(lint v) {
v %= MOD;
if (v < 0) v += MOD;
val = (int)v;
}
mint operator-() const { return mint(-val); }
mint& operator+=(const mint& other) {
val += other.val;
if (val >= MOD) val -= MOD;
return *this;
}
mint& operator-=(const mint& other) {
val -= other.val;
if (val < 0) val += MOD;
return *this;
}
mint& operator*=(const mint& other) {
val = (int)((lint)val * other.val % MOD);
return *this;
}
static mint ipow(mint a, lint p) {
mint ans(1);
while (p > 0) {
if (p & 1) ans *= a;
a *= a;
p >>= 1;
}
return ans;
}
mint inv() const { return ipow(*this, MOD - 2); }
mint& operator/=(const mint& other) { return (*this) *= other.inv(); }
friend mint operator+(mint a, const mint& b) { return a += b; }
friend mint operator-(mint a, const mint& b) { return a -= b; }
friend mint operator*(mint a, const mint& b) { return a *= b; }
friend mint operator/(mint a, const mint& b) { return a /= b; }
friend ostream& operator<<(ostream& os, const mint& m) {
return os << m.val;
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<array<int, 2>> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i][0] >> a[i][1];
}
vector<mint> dp(n);
vector<vector<mint>> sums(100, vector<mint>(n, mint(0)));
for (int i = n - 1; i >= 0; i--) {
dp[i] = mint(1);
int step = a[i][0];
int cnt = a[i][1];
if (step >= 100) {
for (int j = 1; j <= cnt; j++) {
long long nxt = (long long)i + 1LL * j * step;
if (nxt >= n) break;
dp[i] += dp[(int)nxt];
}
} else if (step > 0) {
int p1 = i + step;
if (p1 < n) dp[i] += sums[step][p1];
long long p2 = (long long)i + 1LL * step * (cnt + 1);
if (p2 < n) dp[i] -= sums[step][(int)p2];
}
for (int j = 1; j < 100; j++) {
mint nextSum = (i + j < n) ? sums[j][i + j] : mint(0);
sums[j][i] = nextSum + dp[i];
}
}
cout << dp[0];
return 0;
}
