#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int main()
{
    int a, b, c;
    double s,p;
    scanf("%d %d %d", &a, &b, &c);
    p = 0.5 * (a + b + c);
    s = pow((p * (p - a) * (p - b) * (p - c)), 0.5);
    printf("%1f", s);
    return 0;
}

为什么总是过不了啊