#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define ll long long
#define ld long double
#define pb push_back
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define pii pair<int,int> //
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define pdd pair<double,double>
#define mp make_pair
#define AmirMakaM ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
// solve it
const ull SEED = chrono::steady_clock::now().time_since_epoch().count();
mt19937_64 mrand(SEED);
ull rnd(ull x = ~(0ull)) {return mrand() % x;}
const ll MOD = 1e9 + 7;
const ll INF = 1e16+20;
const int inf = 1e9 + 7;
const ll N = 1e5+1;
const ll M = 2e3+1;
const double pi = 2*acos(0.0);
const int dx[] = {1,-1,0,0}, dy[] = {0,0,1,-1};
void solve() {
ll n;
cin >> n;
ll d[n+1], x[n+1];
for(int i=1; i<=n; i++) cin >> d[i] >> x[i];
//if(1) {
ll ans[n+2] = {}, res = 1;
ans[0] = 1;
for(ll i=1; i<=n; i++) {
if(i!=2) ans[i] += ans[i-1];
res = (res + (min(n,i+x[i]*d[i]) - i)*ans[i] % MOD) % MOD;
ans[i+1] += ans[i];
ans[min(n,i+x[i]*d[i]) + 1] -= ans[i];
}
cout << res << '\n';
//}
/*if(1) {
ll ans[n+1] = {};
ans[1] = 1;
for(ll i=1; i<=n; i++) {
if(!d[i]) continue;
for(ll j=i+d[i]; j<=min(n,i+d[i]*x[i]); j+=d[i]) {
ans[j] = (ans[j] + ans[i]) % MOD;
}
}
ll res = 0;
for(int i=1; i<=n; i++) {
res = (res + ans[i]) % MOD;
}
cout << res << '\n';
}*/
}
int main() {
AmirMakaM;
srand(SEED);
//freopen("walk.in", "r", stdin);
//freopen("walk.out", "w", stdout);
int ttt = 1;
//cin >> ttt;
while(ttt--) {
solve();
}
return 0;
}
