#include <bits/stdc++.h>
#define ff first
#define ss second
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int SZ = 1010;
int n, m; double p;

double dp[SZ][SZ];
int main() {
	cin.tie(0); ios_base::sync_with_stdio(0);
	cin >> n >> m >> p;

	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= m; j++) {
			if (i == 0 && j == 0) {
				continue;
			}

			double a = (i == 0) ? 1e20 : dp[i - 1][j];
			double b = (j == 0) ? 1e20 : dp[i][j - 1];
			if (a > b) {
				swap(a, b);
			}

			double k = min(b - a, p);
			dp[i][j] = a / 2 + (a * k + k * k / 2 + b * (p - k)) / (2 * p);
		}
	}
	cout.precision(10);
	cout << fixed << dp[n - 1][m - 1] << '\n';
}