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