include

include

using namespace std;

int max_of_four(int a, int b, int c, int d) {

return max(max(a,b),max(c,d));

}

int main() {

int a;
int b;
int c;
int d;
cin>>a>>b>>c>>d;
cout<<max_of_four(a,b,c,d);


return 0;

}