T了4个点，R了1个点

#include<bits/stdc++.h>
using namespace std;
int gcd(unsigned long long a,unsigned long long b){
	while(a!=b){
		if(a>b){
			a=(a-1)%b;
			a++;
		}else{
			b=(b-1)%a;
			b++;
		}
	}
	return a;
}
int main(){
	unsigned long long x,gd,lcm=1,lj=0;
	cin>>x;
	int a[x],b[x];
	for(int i=0;i<x;i++){
		cin>>a[i]>>b[i];
	}
	lj=b[0];
	lcm=a[0];
	for(int i=0;i<x;i++){
		while(lj%a[i]!=b[i]){
			lj+=lcm;
//			cout<<lj<<" "<<a[i]<<" "<<b[i]<<endl;
//			_sleep(100);
		}
		gd=gcd(lcm,a[i]);
		lcm*=a[i];
		lcm/=gd;
	}
	cout<<lj;
}