#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <algorithm>
#include <set>
#include <map>
#include <bitset>
#include <cmath>
#include <functional>
#include <iomanip>
#define vll vector<ll>
#define vvvl vector<vvl>
#define vvl vector<vector<ll>>
#define VV(a, b, c, d) vector<vector<d>>(a, vector<d>(b, c))
#define VVV(a, b, c, d) vector<vvl>(a, vvl(b, vll (c, d)));
#define re(c, b) for(ll c=0;c<b;c++)
#define all(obj) (obj).begin(), (obj).end()
typedef long long int ll;
typedef long double ld;
using namespace std;

int main() {
  ll n, m;std::cin >> n >> m;
  ld p;std::cin >> p;
  ld ans = 0;

  re(i, n){
    re(j, m){
      ll num = (i!=0) + (i!=n-1) + (j!=0) + (j!=m-1);
      if(num==0) ans += p;
      if(num==1) ans += p*p;
      if(num==2) ans += p*p*p;
      if(num==3) ans += p*p*p*p;
      if(num==4) ans += p*p*p*p*p;
    }
  }
  cout << fixed << setprecision(20) << ans << "\n";
}