func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAX_N = 300;   const int mod = 1e9 + 7;   const int INF = 0x3f3f3f3f;   const double eps = 1e-6;   string s;   int gx[] = {0, 0, 1, -1};   int gy[] = {1, -1, 0, 0};   bool used[MAX_N][MAX_N];   bool check(int x, int y) {     int cnt = 0;     for (int i = 0; i < 4; ++i) {       int nx = x + gx[i];       int ny = y + gy[i];       if (used[nx][ny]) ++cnt;     }     return cnt == 1;   }   bool solve() {     cin >> s;     int x = 100, y = 100;     used[x][y] = true;     for (auto &ch : s) {       if (ch ==  U )         ch = ch -  U  +  3 ;       else if (ch ==  D )         ch = ch -  D  +  2 ;       else if (ch ==  L )         ch = ch -  L  +  1 ;       else         ch = ch -  R  +  0 ;     }     for (auto ch : s) {       x += gx[ch -  0 ];       y += gy[ch -  0 ];       if (used[x][y]) return false;       used[x][y] = true;       if (!check(x, y)) return false;     }     return true;   }   signed main() {     ios::sync_with_stdio(false);     cin.tie(nullptr);     int t = 1;     while (t--) {       if (solve())         cout <<  OK  <<   n ;       else         cout <<  BUG  <<   n ;     }     return 0;   }   