#include <stdio.h>

int main()
{
	int a = 0; 
	int b = 0; 
	int c = 0; 
	int d = 0;  
	int max1 = 0; 
	int max2 = 0; 
	int max3 = 0;
	scanf("%d %d %d %d", &a, &b, &c, &d); 
	max1 = (a > b ? a : b); 
	max2 = (c > d ? c : d); 
	max3 = (max1 > max2 ? max1 : max2); 
	printf("%d\n", max3); 
	return 0; 
}