#include <stdio.h>

int max(int x,int y);
int main(void){
	
	int a,b,c,d;
	scanf("%d %d %d %d",&a,&b,&c,&d);
	printf("%d",max(max(a,b),max(c,d)));
	return 0;
}

int max(int x,int y){
	return (x>y)?x:y;
	
}