#include<bits/stdc++.h>
using namespace std;
int main(){
	int a,b,c,d,x;
	cin>>a>>b>>c>>d;
	x=a;
	if(b>x) x=b;
	if(c>x) x=c;
	if(d>x) x=d;
	cout<<x;
}
/**************************************************************
	Problem: 1305
	User: zengyixuan
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/