板子中国剩余定理

#include<cstdio>
#include<bits/stdc++.h>
#define ll long long 
using namespace std;
int n,a[11],b[11];
long long M=1,x,y,ans;
ll exgcd(ll A,ll B,ll &x,ll &y)
{
	if(B==0) {
		
		x=1;
		y=0;
		return A;
	}
	ll k=exgcd(B,A%B,x,y);
	ll z=x;
	x=y;
	y=z-y*(A/B);
	return k;
}
int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d%d",&b[i],&a[i]);
		M*=b[i];
	}
	for(int i=1;i<=n;i++)
	{
		ll mi=M/b[i];//记得开longlong！！我忘开直接100变80了
		ll Gcd=exgcd(mi,b[i],x,y);
	//	cout<<x<<' '<<ans;
		ans=((ans+x*mi*a[i])%M+M)%M;
		
	}
	cout<<(ans%M+M)%M;
}