#include <stdio.h>

int MAX(int x , int y)
{
    if(x > y)
        return x;
    else
        return y;
}

int main() 
{
    int num1 = 0;
    int num2 = 0;
    int num3 = 0;
    int num4 = 0;
    scanf("%d %d %d %d", &num1,&num2,&num3,&num4);
    int max1 = MAX(num1 , num2);
    int max2 = MAX(num3 , num4);
    int max3 = MAX(max1 , max2);
    printf("%d", max3);

    
    return 0;
}