参考答案：

#include<iostream>

using namespace std;

int main() 
{
    int a, b, c;
    double p, s;

    cin >> a >> b >> c; 
    p = (a + b + c) * 1.0 / 2;
    s = sqrt(p * (p - a) * (p - b) * (p - c));

    printf("area=%.2f", s);

    return 0;
}