int main(){
  
int h1,m1,h2,m2;

while(cin>>h1>>m1>>h2>>m2){
  
  if((h2<h1)||(h2==h1&&m2<m1)){
    
cout<<(24-(h1+1))*60+(60-m1)+h2*60+m2<<endl;
}
else if(h1==0&&h2==0&&m1==0&&m2==0){ break; }

else {cout<<(h2*60+m2)-(h1*60+m1) <<endl; }
}
  return 0;