#include<stdio.h>

int max_of_four(int a, int b, int c, int d)
{
    int max=a;
    
    if(max < b)
        max = b;
    if(max  < c)
        max = c;
    if(max < d)
        max = d;
    
    return max;
}

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;
}