#include <bits/stdc++.h>   using namespace std;   void _fill_int(int* p, int val, int rep) {     int i;     for (i = 0; i < rep; i++) p[i] = val;   }   signed long long GETi() {     signed long long i;     scanf( %lld , &i);     return i;   }   int N;   map<vector<int>, double> M[64];   int st[64], num[64];   double dodo(int top, vector<int> V) {     int otop, i, x, y, z, ng = 0;     otop = top = st[top];     sort(V.begin(), V.end());     vector<int> VV = V;     if (M[top].find(V) != M[top].end()) return M[top][V];     if (num[top] == 3) V.push_back(top), top = 0, ng = 1;     double ma[4] = {0, 1e15, 1e15, 1e15};     int pre = -1;     for (i = 0; i < V.size() - ng; i++) {       if (pre == V[i]) continue;       pre = V[i];       x = V[i] % 4;       y = V[i] / 4 % 4;       z = V[i] / 16;       vector<int> V2 = V;       V2.erase(V2.begin() + i);       if (x && y && z) {         if (top % 4 == 0) ma[y] = min(ma[y], dodo(top + y * 1, V2));         if (top / 4 % 4 == 0) ma[y] = min(ma[y], dodo(top + y * 4, V2));         if (top / 16 == 0 && top % 4) ma[y] = min(ma[y], dodo(top + y * 16, V2));       }       if (z && y) {         if (x) {           V[i] = 4 + x;           if (top % 4 == 0) ma[z] = min(ma[z], dodo(top + z * 1, V));           if (top / 4 % 4 == 0) ma[z] = min(ma[z], dodo(top + z * 4, V));           if (top / 16 == 0 && top % 4) ma[z] = min(ma[z], dodo(top + z * 16, V));         } else {           if (top % 4 == 0) ma[z] = min(ma[z], dodo(top + z * 1, V2));           if (top / 4 % 4 == 0) ma[z] = min(ma[z], dodo(top + z * 4, V2));           if (top / 16 == 0 && top % 4)             ma[z] = min(ma[z], dodo(top + z * 16, V2));         }       }       if (y && x) {         if (z) {           V[i] = z + 4;           if (top % 4 == 0) ma[x] = min(ma[x], dodo(top + x * 1, V));           if (top / 4 % 4 == 0) ma[x] = min(ma[x], dodo(top + x * 4, V));           if (top / 16 == 0 && top % 4) ma[x] = min(ma[x], dodo(top + x * 16, V));         } else {           if (top % 4 == 0) ma[x] = min(ma[x], dodo(top + x * 1, V2));           if (top / 4 % 4 == 0) ma[x] = min(ma[x], dodo(top + x * 4, V2));           if (top / 16 == 0 && top % 4)             ma[x] = min(ma[x], dodo(top + x * 16, V2));         }       }       V[i] = pre;     }     int sum = 1;     if (ma[1] >= 1e15) ma[1] = 0, sum += 1;     if (ma[2] >= 1e15) ma[2] = 0, sum += 2;     if (ma[3] >= 1e15) ma[3] = 0, sum += 2;     if (sum == 6) return M[otop][VV] = 0;     M[otop][VV] = (1 + ma[1] / 6 + ma[2] / 3 + ma[3] / 3) / (1 - sum / 6.0);     return M[otop][VV] =                (1 + ma[1] / 6 + ma[2] / 3 + ma[3] / 3) / (1 - sum / 6.0);   }   void solve() {     int f, i, j, k, l, x, y, x2, y2, z;     cin >> N;     string S;     for (i = 0; i < 64; i++) {       x = i % 4;       y = i / 4 % 4;       z = i / 16;       st[i] = (z > x) ? (x * 16 + y * 4 + z) : i;       num[i] = (x > 0) + (y > 0) + (z > 0);     }     vector<int> V;     for (i = 0; i < N; i++) {       cin >> S;       x = 0;       for (y = 0; y < 3; y++) {         if (S[y] ==  R ) x += 1 << (y * 2);         if (S[y] ==  G ) x += 2 << (y * 2);         if (S[y] ==  B ) x += 3 << (y * 2);       }       if (i < N - 1) V.push_back(st[x]);     }     (void)printf( %.12lf n , dodo(st[x], V));   }   int main(int argc, char** argv) {     string s;     if (argc == 1) ios::sync_with_stdio(false);     for (int i = 1; i < argc; i++) s += argv[i], s +=   n ;     for (int i = s.size() - 1; i >= 0; i--) ungetc(s[i], stdin);     solve();     return 0;   }