#include <bits/stdc++.h>
typedef long long ll;
#define FOR(i,x,y) for(ll i=x; i<y; i++)
#define FORNEG(i,x,y) for(ll i=x; i>y; i--)
using namespace std;
multiset<vector<ll>> sus[505][505];
ll sums[505][505];
ll dp[100005];
int main(){
ll n;
cin >> n;
FOR(i,0,n+1) dp[i] = 0;
FOR(i,0,505) FOR(j,0,505) sus[i][j].clear(), sums[i][j] = 0;
dp[0] = 1;
FOR(i,0,n){
FOR(j,1,501){
ll mod = i%j;
while(!sus[j][mod].empty()){
vector<ll> temps = *sus[j][mod].begin();
if (temps[0] <= i){
sums[j][mod] -= temps[1];
sums[j][mod] += 1000000007;
sums[j][mod] %= 1000000007;
sus[j][mod].erase(sus[j][mod].find(temps));
}
else break;
}
dp[i] += sums[j][mod];
dp[i] %= 1000000007;
}
ll a,b;
cin >> a >> b;
if (a==0) continue;
ll lim = i + a*b + 1;
if (a > 500){
ll cur = i;
cur += a;
while (cur < lim && cur < 100005){
dp[cur] += dp[i];
dp[cur] %= 1000000007;
cur += a;
}
}else{
sus[a][i%a].insert({lim, dp[i]});
sums[a][i%a] += dp[i];
sums[a][i%a] %= 1000000007;
}
}
ll ans = 0;
FOR(i,0,n){
ans += dp[i];
}
cout << ans%1000000007;
}
