#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define inf 10e17
#define rep(i,n) for(long long i=0; i<n; i++)
#define repr(i,n,m) for(long long i=m; i<n; i++)
#define mod 1000000007
#define sorti(x) sort(x.begin(), x.end())
#define sortd(x) sort(x.begin(), x.end(), std::greater<long long>())
#define debug(x) std::cerr << (x) << std::endl;
#define roll(x) for (auto&& itr : x) { cerr << (itr) << " "; }

template <class T> inline void chmax(T &ans, T t) { if (t > ans) ans = t;}
template <class T> inline void chmin(T &ans, T t) { if (t < ans) ans = t;}

int main() {
  ll n,m;
  double p;
  cin >> n >> m >> p;
  double ans = 0;
  cout << fixed << setprecision(15);

  double p2 = p * p;
  double p3 = p2 * p;
  double p4 = p3 * p;
  double p5 = p4 * p;

  if (n == 1 || m == 1) {
    if (n == 1 && m == 1) {
      ans = p;
    } else {
      auto len = (m == 1) ? n : m;
      ans += p2 * 2;
      ans += p3 * (len - 2);
    }
  } else {
    auto l1 = n - 2, l2 = m - 2;
    ans += p3 * 4;
    ans += (l1 + l2) * 2 * p4;
    ans += (n - 2) * (m - 2) * p5;
  }

  cout << ans << endl;
}