#include <stdio.h>

int main() {
    int a, b, c, d, num1, num2= 0;
    scanf("%d %d %d %d",&a, &b, &c, &d);
    num1 = a > b?a:b;
    num2 = c > d?c:d;
    printf("%d",num1 > num2?num1:num2);
    
    return 0;
}