#include <bits/stdc++.h>
#define LLI long long int
#define FOR(v, a, b) for(LLI v = (a); v < (b); ++v)
#define FORE(v, a, b) for(LLI v = (a); v <= (b); ++v)
#define REP(v, n) FOR(v, 0, n)
#define REPE(v, n) FORE(v, 0, n)
#define REV(v, a, b) for(LLI v = (a); v >= (b); --v)
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define ITR(it, c) for(auto it = (c).begin(); it != (c).end(); ++it)
#define RITR(it, c) for(auto it = (c).rbegin(); it != (c).rend(); ++it)
#define EXIST(c,x) ((c).find(x) != (c).end())
#define fst first
#define snd second
#define popcount __builtin_popcount
#define UNIQ(v) (v).erase(unique(ALL(v)), (v).end())
#define bit(i) (1LL<<(i))

#ifdef DEBUG
#include <misc/C++/Debug.cpp>
#else
#define dump(...) ((void)0)
#endif

#define gcd __gcd

using namespace std;
template <class T> constexpr T lcm(T m, T n){return m/gcd(m,n)*n;}

template <typename I> void join(ostream &ost, I s, I t, string d=" "){for(auto i=s; i!=t; ++i){if(i!=s)ost<<d; ost<<*i;}ost<<endl;}
template <typename T> istream& operator>>(istream &is, vector<T> &v){for(auto &a : v) is >> a; return is;}
template <typename T, typename U> bool chmin(T &a, const U &b){return (a>b ? a=b, true : false);}
template <typename T, typename U> bool chmax(T &a, const U &b){return (a<b ? a=b, true : false);}
template <typename T, size_t N, typename U> void fill_array(T (&a)[N], const U &v){fill((U*)a, (U*)(a+N), v);}

struct Init{
  Init(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(12);
    cerr << fixed << setprecision(12);
  }
}init;



int main(){
  LLI N, M;
  double P;
  while(cin >> N >> M >> P){
    double ans = 0;

    LLI c0 = 0, c1 = 0, c2 = 0, c3 = 0, c4 = 0;

    if(N == 1 and M == 1){
      c0 = 1;
    }else{
      if(N == 1){
        c1 = 2;
        c2 = M-c1;
      }else if(M == 1){
        c1 = 2;
        c2 = N-c1;
      }else{
        c2 = 4;
        c3 = (N-2) * 2 + (M-2) * 2;
        c4 = N * M - c3 - c2;
      }
    }

    ans += P * pow(P, 0) * c0;
    ans += P * pow(P, 1) * c1;
    ans += P * pow(P, 2) * c2;
    ans += P * pow(P, 3) * c3;
    ans += P * pow(P, 4) * c4;


    cout << ans << endl;
  }
  
  return 0;
}