#include <bits/stdc++.h>
using namespace std;

#define tsolve int t; cin >> t; while(t--) solve
#define debug(x) cerr << __LINE__ << ": "#x" = " << (x) << endl
#define all(x) ::begin(x), ::end(x)
#define sz(x) (int)::size(x)
using ll = long long;
using ld = long double;

void solve() {
	ll n, m, p;
	cin >> n >> m >> p;
	vector<vector<ld>> dp(n, vector<ld>(m));

	dp[n-1][m-1] = 0;
	for (int i=n-1; i>=0; i--) {
		for (int j=m-1; j>=0; j--) {
			if (i == n-1 && j == m-1) continue;

			if (i == n-1) {
				dp[i][j] = dp[i][j+1] + p / 4.0L;
			} else if (j == m-1) {
				dp[i][j] = dp[i+1][j] + p / 4.0L;
			} else {
				ld diff = min<ld>(p, abs(dp[i+1][j] - dp[i][j+1]));
				ld prob = (p + diff) / (2*p);
				dp[i][j] = prob * (min(dp[i+1][j], dp[i][j+1]));
				dp[i][j] += (prob-0.5) * diff / 2;
				dp[i][j] += (1-prob) * max(dp[i+1][j], dp[i][j+1]);
			}
		}
	}
	cout << dp[0][0] << '\n';
}

int main() {
	cin.tie(0)->sync_with_stdio(false);
	cout << setprecision(16);
	solve();
}