#include<iostream> u

#include<iostream>
using namespace std;
int main(){
int a,b,c,d;
cin>>a>>b>>c>>d;
if(ac&&bd){
cout<<"0"<<endl;
}
else if(ac&&b<d){
cout<<d-b<<endl;
}
else if(a!=c&&bd){
cout<<(c-a)*60<<endl;
}
else{
cout<<(c-a)*60-(b-d)<<endl;
}
return 0;
}