#include <stdio.h>
int main(){
    int a,b,c,d,x,y,z;
    scanf("%d %d %d %d",&a,&b,&c,&d);
    x=a>b?a:b;
    y=c>d?c:d;
    z=x>y?x:y;
    printf("%d",z);

    return 0;
}