#include <stdio.h>
#include<stdbool.h>

int max_of_four(int a, int b, int c, int d) {
    
    while (true) {
        if ( (a > b && a > c) && (a > d) ) {
            return a;
        } else if ((b > a && b > c) && (b > d)) {
            return b;
        } else if ( (c > a && c > b) && (c > d)) {
            return c;
        } else if ((d > a && d > b) && (d > c)) {
            return d;
        }
    }
    return 0;
    
}


int main() {
    int a, b, c, d;
    scanf("%d %d %d %d", &a, &b, &c, &d);
    int ans = max_of_four(a, b, c, d);
    printf("%d", ans);
		return 0;
}    
    return 0;


/*
	I want to share my solution to this challenge.

I used a while loop to compare which letter is greater than the rest.

However, I would like to receive some suggestions to see if my solution is really valid or if it can be improved. Thank you very much.

*/
}