为什么我把“S+0.05”的“+0.05”去掉后就给Accepted了？

#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
int main()
{
	double a, b, c;
	cin >> a >> b >> c;
	double p = 0.5 * (a + b + c);
	double S = sqrt(p * (p - a) * (p - b) * (p - c));
	printf("%.1lf", S + 0.05);
	return 0;
}