#include<iostream>
#include<cmath>
#include<string>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#define FRO freopen("in.txt","r",stdin)

using namespace std;

int main()
{
//FRO;
	int a,b,c,i,j,k,tc,t=0;
    int n,m,cnt=0,h,h1,m1,cnt1;
    while(scanf("%d%d%d%d",&h,&m,&h1,&m1))
    {
        if(h==m&& m==h1&& h1==m1&& m1==0)return 0;
        //if(t>0){printf("\n");t++;}
        cnt=0;cnt1=0;
        if(m1>=m)cnt+=m1-m;
        else {cnt+=m1+(60-m);}
        if(h==h1)
        {
            if(m>m1)cnt1+=h1+(23-h);
        }
        else if(h>h1)
        {
            cnt1+=h1+(23-h);
        }
        else cnt1+=h1-h;
        printf("%d\n",cnt+(cnt1*60));
    }

return 0;
}