#include<iostream>
using namespace std;
int main()
{
   
 
int a;
int b;
int c;  
int d;
 
 while(cin>>a>>b>>c>>d && 0<=a<=23 && 0<=c<=23 && 0<=b<=59 && 0<=d<=59)
 {
                     
                 
     if( a==0 && b==0 && c==0 && d==0)
     break;
     if(a>c)
     {int y=((c-a)+24)*60;
      cout<<y+(d-b)<<endl;}
               if(a==b==c==d && a!=0)
               cout<<0<<endl;
    
     if(a<c)
     {int x=(c-a)*60;
     cout<<x+(d-b)<<endl;}
     
                if(a==c && b<d)
                {cout<<d-b<<endl;}
                if(a==c && b>d)
                {cout<<1440+(d-b)<<endl;}
                  
                      
                       }

 return 0;
}