#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) begin(v),end(v)
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
using ll = long long;
using pii = pair<int, int>;
constexpr ll INF = 1ll<<30;
constexpr ll longINF = 1ll<<60;
constexpr ll MOD = 1000000007;
constexpr bool debug = false;
//---------------------------------//

int main() {
	int N, M;
	double P;
	cin >> N >> M >> P;
	double Q = 1 - P;
	
	if (N == 1 && M == 1) { printf("%.7f\n", P); return 0; }
	if (N > M) swap(N, M);
	if (N == 1) { printf("%.16f\n", pow(P, 2) * 2 + (M >= 3 ? pow(P, 3) * (M - 2): 0)); return 0; }
	ll NM = (ll)N * M;
	double ee = pow(P, 3);
	double em = pow(P, 4);
	double mm = pow(P, 5);
	
	double ans = ee * 4;
	if (N >= 3) ans += 2 * (N - 2) * em;
	if (M >= 3) ans += 2 * (M - 2) * em;
	if (N >= 3 && M >= 3) ans += (ll)(N - 2) * (M - 2) * mm;
	printf("%.16f\n", ans);
	
}