#include <bits/stdc++.h>

using namespace std;
#define int long long
#define app push_back
#define all(x) (x).begin(),(x).end()
#ifdef LOCAL
#define debug(...) [](auto...a){ ((cout << a << ' '), ...) << endl;}(#__VA_ARGS__, ":", __VA_ARGS__)
#define debugv(v) do {cout<< #v <<" : {"; for(int i=0;i<v.size();++i) {cout << v[i];if(i+1!=v.size()) cout << ","; }cout <<"}"<< endl;} while(0)
#else
#define debug(...)
#define debugv(v)
#endif
#ifdef LOCAL
#define __int128 long long
#endif // LOCAL
const int p=998244353;
int po(int a,int b) {if(b==0) return 1; if(b==1) return a; if(b%2==0) {int u=po(a,b/2);return (u*1LL*u)%p;} else {int u=po(a,b-1);return (a*1LL*u)%p;}}
int inv(int x) {return po(x,p-2);}
mt19937 rnd;
const double inf=1e18;
const int maxn=1e3+5;
double dp[maxn][maxn];
int32_t main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int n,m;double p;cin>>n>>m>>p;--n;--m;
    for(int i=0;i<=n;++i)
    {
        for(int j=0;j<=m;++j)
        {
            if(i==0 && j==0) {dp[i][j]=0;continue;}
            double x1=(i==0 ? inf : dp[i-1][j]);
            double y1=(j==0 ? inf : dp[i][j-1]);
            double mi=min(x1,y1);double a=abs(y1-x1);
            if(a<=p)
            {
                dp[i][j]=mi+(1/2.0)*(a*(p-a)/p)+(1/2.0)*(a*a/(2.0*p));
            }
            else
            {
                dp[i][j]=mi+p/4.0;
            }
        }
    }
    cout<<setprecision(25)<<dp[n][m];
    return 0;
}