#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
int Max4(int a, int b, int c, int d)
{
	int Max2(int a, int b);
		int m;
		m = Max2(a, b);
		m = Max2(m, c);
		m = Max2(m, d);
		return m;
	}
	int Max2(int a, int b)
	{
		if (a >= b)
			return a;
		else
			return b;
	}
	int main()
	{
		int x, y, z, n;
		int max;
			scanf("%d %d %d %d", &x, &y, &z, &n);
		max = Max4(x,y,z,n);
		printf("%d\n", max);
		system("pause");
		return 0;
	}