模板代码:
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define fi first
#define se second
const ll mod=998244353;
const int N=2e5+10;
#define int llint n,m[300],r[300];
int exgcd(int a,int b,int &x,int &y){if(b==0){x=1,y=0;return a;}int d=exgcd(b,a%b,y,x);y-=a/b*x;return d;
}
ll crt(ll m[],ll r[]){ll M=1,ans=0;for(int i=1;i<=n;i++) M*=m[i];for(int i=1;i<=n;i++){ll c=M/m[i],x,y;exgcd(c,m[i],x,y);ans=(ans+r[i]*c*x%M)%M;}return (ans%M+M)%M;
}
void solve(){cin>>n;for(int i=1;i<=n;i++){cin>>m[i]>>r[i];}cout<<crt(m,r);
}signed main(){ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);int t=1;//cin>>t;while (t--){solve();}return 0;
}