Maxi_Task

#include <iostream>
#include <iomanip>

using namespace std;

int C(int n, int k) {
    double ans = 1;
    for (int i=1; i<=k; i++)
        ans = ans * (n-k+i) / i;
    return (int) (ans + 0.01);
}

double fast_pow(double a, int b) {
    if (b == 0) return 1;
    else {
        double t = fast_pow(a, b/2);
        if (b%2) return t*t*a;
        else return t*t;
    }
}

int main()
{
    int m, n, k;
    cin >> m >> n >> k;

    double ans = 0.0;

    for (int i=1; i<=k; i++)
        ans += C(k,i) * fast_pow(1./m/n, i) * fast_pow(1. - 1./m/n, k-i);

    ans *= m*n;

    cout << fixed << setprecision(10) << ans;

    return 0;
}