import java.io.*;
import java.util.*;

public class Main
{
  public static void main(String arg[]) throws Exception
	{
		BufferedReader buffer=new BufferedReader(new InputStreamReader(System.in));
		String str=buffer.readLine();
		int arr_time,last=1000;
		int num=Integer.parseInt(str);		
    Vector vc=new Vector(10,2);

		int ii,jj,kk;
		int speed;
		float tmp;
		StringTokenizer st;
		
			  while(num!=0)
	  {

			for(ii=0,last=1000;ii<num;ii++)
			{
				str=buffer.readLine();
				st=new StringTokenizer(str);
				speed=Integer.parseInt(st.nextToken());
				kk=Integer.parseInt(st.nextToken());
				if(kk>=0)
				{
					 tmp=(float)(3600*4.5)/speed+kk;
           /*printf("tmp:%f  %d",tmp,(int)tmp);*/
          // System.out.println(tmp);
           if(tmp-(int)tmp<.001)
           arr_time=(int )tmp;
           else
           arr_time=1+(int )tmp;
           last= ( arr_time<last)?arr_time:last;

					}
				
				//stem.out.println(last);
			}
			Integer it=new Integer(last);
			vc.add(it);
			str=buffer.readLine();
		  num=Integer.parseInt(str);
					

	}
	 while(!vc.isEmpty())

    {

      System.out.println(((Integer)vc.firstElement()).intValue());
      vc.remove(0);

      }
//其实最佳的就是最早的，简单的问题莫夫扎花
 }

}