#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MOD = 1e9+7;
signed main(){
int n;
cin >> n;
vector<int> d(n+1), x(n+1);
for(int i = 0; i < n; i++){
cin >> d[i] >> x[i];
}
vector<int> ans(n, 0);
ans[0]=1;
int totalans = 0;
vector<vector<int>> pref(n+5, vector<int>(370));
for(int i = 0; i < n; i++){
for (int j = 0; j <= 360; j++) {
if (i-j >= 0)pref[i][j]+=pref[i-j][j];
pref[i][j]%= MOD;
ans[i] +=pref[i][j];
ans[i] %= MOD;
}
if(d[i]>360){
for(int j = 1; j <= x[i]; j++){
int k = i+d[i]*j;
if(k>=n)break;
ans[k]+=ans[i];
ans[k]%=MOD;
}
}
else{
pref[i][d[i]]+= ans[i];
pref[i][d[i]] %= MOD;
int r = min(i+(x[i]+1)*d[i],n);
pref[r][d[i]] +=MOD-ans[i];
pref[r][d[i]] %= MOD;
}
totalans+=ans[i];
totalans%=MOD;
}
cout << totalans << "\n";
}
