#include <iostream>
using namespace std;
int main()
{
	int a,b,c,d,x;
	cin >> a>>b >> c>>d;
	a = x;
	if (b>x)
	{
		x = b;
	}
	if (c>x)
	{
		x = c;
	}
	if (d>x)
	{
		x = d;
	}
	cout << x;
 } 
/**************************************************************
	Problem: 1305
	User: xiaomingze
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/