#include <bits/stdc++.h>

using namespace std;
double dp[105][105][105];
int main()
{
    int a,b,c;
    scanf("%d%d%d",&a,&b,&c);
    for(int i=99;i>=a;i--)
    {
        for(int j=99;j>=b;j--)
        {
            for(int k=99;k>=c;k--)
            {
                dp[i][j][k]=1.0*i/(i+j+k)*dp[i+1][j][k]+1.0*j/(i+j+k)*dp[i][j+1][k]+1.0*k/(i+j+k)*dp[i][j][k+1]+1;
            }
        }
    }
    printf("%.6f\n",dp[a][b][c]);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
 
#define ff              first
#define ss              second
#define int             long long
#define pb              push_back
#define pii             pair<int,int>
#define vi              vector<int>
#define mii             map<int,int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             1000000007
#define inf             1e18
#define ps(x,y)         cout<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
#define w(x)            int x; cin>>x; while(x--)
#define pw(b,p)         pow(b,p) + 0.1
#define endl            "\n"
mt19937                 rng(chrono::steady_clock::now().time_since_epoch().count());


void __print(int32_t x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
 
char myHeap[200 * 1024 * 1024];
int sz = 0;
void assert_tle(bool q) { while (!q); }
void* operator new  ( std::size_t count ) {
    sz += count;
    assert_tle(sz <= 200 * 1024 * 1024);
    return myHeap + sz - count;
}
 
void operator delete (void *ptr) { }
 
 
void fastIO()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
}

double memo[100][100][100];

double dp(int a,int b,int c)
{
    //debug(a,b,c);
    if(a>=100||b>=100||c>=100) return 0;
    if(memo[a][b][c]) return memo[a][b][c];
    double tot=a+b+c;
    double pa=a/tot;
    double pb=b/tot;
    double pc=c/tot;

    double ans=pa*(1+dp(a+1,b,c))+pb*(1+dp(a,b+1,c))+pc*(1+dp(a,b,c+1));
    memo[a][b][c]=ans;

    return ans;
}

void solve()
{
    int a,b,c;
    cin>>a>>b>>c;
    memset(memo,0.0,sizeof memo);
    cout<<fixed<<setprecision(9);
    cout<<dp(a,b,c);

}
 
int32_t main()
{
    fastIO();
    //w(t)
    {
        solve();
        cout<<endl;
    }
    return 0;
}