#include<bits/stdc++.h>
using namespace std;
#define int long long
#define vec vector
const int MOD = 1e9 + 7;
const int SQN = 1000;
int32_t main() {
int N;
cin >> N;
vec<int> D(N), X(N);
for(int i = 0; i<N; i++) {
cin >> D[i];
cin >> X[i];
}
vec<int> f(N, 1);
vec<vec<int>> fsum(N, vec<int>(SQN, 1));
for(int i = N-2; i>=0; i--) {
if(D[i] == 0) {}
else if(D[i] >= SQN) {
for(int j = 1; j<=X[i] && i+(j*D[i]) < N; j++) {
f[i] += f[i+(j*D[i])];
f[i] %= MOD;
assert(i+(j*D[i]) < N);
}
}
else {
f[i] += ((i+D[i]) < N ? fsum[i+D[i]][D[i]] : 0ll) + MOD - (i+(X[i]+1)*D[i] < N ? fsum[i+(X[i]+1)*D[i]][D[i]] : 0ll);
f[i] %= MOD;
}
for(int j = 1; j<SQN; j++) {
fsum[i][j] = f[i] + ((i+j) < N ? fsum[i+j][j] : 0);
}
}
cout << f[0] << '\n';
}
