#include <bits/stdc++.h>
using namespace std;
#define lf "\n"
#define ff endl
#define _ << ' ' <<
#define all(x) begin(x),end(x)
#define rall(x) rbegin(x),rend(x)
#define infos(str) do { fprintf(stderr, str"\n"); } while(0)
#define infor(str, ...) do { fprintf(stderr, str, __VA_ARGS__); } while(0)
#define infof(str, ...) do { fprintf(stderr, str"\n", __VA_ARGS__); } while(0)
#ifndef DEBUG
#undef infos
#undef infor
#undef infof
#define infos(str)
#define infor(str, ...)
#define infof(str, ...)
#endif
using ll = long long;
constexpr int LOG = 20;
constexpr int MOD = 1e9+7;
constexpr int MAXN = 1e5+7;
int main(void) {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int N; cin >> N;
vector<ll> V(N), K(N);
for(int i = 0; i < N; ++i)
cin >> V[i] >> K[i];
vector<ll> dp(N);
vector<unordered_map<int, ll>> pfx(N);
auto calc = [&](ll i, ll k, auto &&calc) -> ll {
if(i >= N) return 0;
if(pfx[i].find(k) != pfx[i].end())
return pfx[i][k];
infof("calc: %d [%d]", i, k);
return pfx[i][k] = (dp[i] + calc(i + k, k, calc)) % MOD;
};
auto sum = [&](ll i, ll v, ll k) {
ll mx_idx = (i + V[i] * ((N - 1 - i) / V[i]));
ll l = min(mx_idx, i) + v, r = min(mx_idx, i + v * k) + v;
ll pfx_l;
if(l >= N)
pfx_l = 0;
else pfx_l = pfx[l][v];
ll pfx_r;
if(r >= N)
pfx_r = 0;
else pfx_r = pfx[r][v];
infof("sum: i = %lld | v = %lld | k = %lld", i, v, k);
infof("... -> (l, r) = [%lld, %lld): [%lld, %lld)", l, r, pfx_l, pfx_r);
return (pfx_l - pfx_r + MOD) % MOD;
};
for(int i = N - 1; i >= 0; i--) {
dp[i] = 1;
if(V[i] == 0 || i + V[i] >= N) continue;
calc(i + V[i], V[i], calc);
dp[i] += sum(i, V[i], K[i]);
}
for(int i = 0; i < N; ++i) {
infos("-------");
infof("%d: %lld", i, dp[i]);
for(auto [k, v]: pfx[i])
infof("... -> %d: %lld", k, v);
infos("");
}
cout << dp[0] << lf;
}
