#include //#include //#include // #include using namespace std; #define rep(i, a) for (int i = (int)0; i < (int)a; ++i) #define repl(i, a) for (long long i = (long long)0; i < (long long)a; ++i) #define rrep(i, a) for (int i = (int)a; i > -1; --i) #define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i) #define REPL(i, a, b) for (long long i = (long long)a; i < (long long)b; ++i) #define RREP(i, a, b) for (int i = (int)a; i > b; --i) #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define popcount __builtin_popcount #define popcountll __builtin_popcountll #define fi first #define se second using ll = long long; constexpr ll mod = 1e9 + 7; constexpr ll mod_998244353 = 998244353; constexpr ll INF = 1LL << 60; // #pragma GCC target("avx2") // #pragma GCC optimize("O3") // #pragma GCC optimize("unroll-loops") //using lll=boost::multiprecision::cpp_int; // using Double=boost::multiprecision::number>;//仮数部が1024桁 template inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } ll mypow(ll x, ll n, const ll &p = -1) { // x^nをmodで割った余り if (p != -1) { x = (x % p + p) % p; } ll ret = 1; while (n > 0) { if (n & 1) { if (p != -1) ret = (ret * x) % p; else ret *= x; } if (p != -1) x = (x * x) % p; else x *= x; n >>= 1; } return ret; } struct myrand{ random_device seed; mt19937 mt; myrand():mt(seed()){} int operator()(int a,int b){//[a,b) uniform_int_distributiondist(a,b-1); return dist(mt); } }; // using namespace atcoder; //------------------------ //------------------------ //------------------------ //------------------------ //------------------------ double dp[51][51][51][51]; void solve() { int a,b,c,n; cin>>a>>b>>c>>n; rep(i,n+1)rep(j,a+1)rep(k,b+1)rep(x,c+1)dp[i][j][k][x]=0; dp[0][a][b][c]=1; rep(i,n){ rep(j,a+1){ rep(k,b+1){ rep(x,c+1){ if(dp[i][j][k][x]==0)continue; double prod=j*k+k*x+x*j; double div=(j+k+x)*(j+k+x-1)/2; prod/=div; dp[i+1][j][k][x]+=dp[i][j][k][x]*prod; prod=j*(j-1)/2; prod/=div; dp[i+1][j-1][k][x]+=dp[i][j][k][x]*prod; prod=k*(k-1)/2; prod/=div; dp[i+1][j][k-1][x]+=dp[i][j][k][x]*prod; prod=x*(x-1)/2; prod/=div; dp[i+1][j][k][x-1]+=dp[i][j][k][x]*prod; } } } } double white=0,black=0,brown=0; rep(A,a+1){ rep(B,b+1){ rep(C,c+1){ white+=dp[n][A][B][C]*(a-A); black+=dp[n][A][B][C]*(b-B); brown+=dp[n][A][B][C]*(c-C); } } } cout<