#include<iostream>
#include<cmath>
#include<stdio.h>
using namespace std;
int main()
{
	
	int n;
	while(cin>>n&&n!=0)
	{
		double v,t,x;
		double min=100000;
		for(int i=0;i<n;i++)
		{
			cin>>v>>t;
			if(t>0&&(x=t+4.5*3600/v)<min)
        min=x;	
		}
cout<<ceil(min)<<endl;
	}
	return 0;
}