C++ :

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
	int a,b,c;
	cin>>a>>b>>c;
	double sum=0;
	for (int i=1; i<=a; i++) sum+=i;
	for (int i=1; i<=b; i++) sum+=i*i;
	for (int i=1; i<=c; i++) sum+=1.0/i;
	printf("%.2lf\n",sum);
	return 0;
}