func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, r;   int main() {     cin >> n >> r;     int ans = 0, Max = -1, mark = false;     for (int i = 1; i <= r; i++) {       int t = i, b = r, num = 0, cnt = 0;       while (t > 0 && b > 0) {         bool flag = false;         if (b > t) {           int c = b / t - 1;           num += c;           b -= t * c;           if (b > t) {             b -= t;             num++;           }           flag = true;         } else {           if (t > b) {             int c = t / b - 1;             num += c;             t -= b * c;             if (t > b) {               t -= b;               num++;             }           }         }         cnt++;         if (t == b) {           num++;           t -= b;           cnt++;           if (b == r) cnt--;           if (cnt > Max && (max(b, t) == 1 && min(b, t) == 0) && num == n) {             if (!flag)               mark = true;             else               mark = false;             Max = cnt;             ans = i;           }         }       }     }     if (Max == -1) {       cout <<  IMPOSSIBLE  << endl;       return 0;     }     string s;     int t = ans, b = r;     if (mark) swap(b, t);     while (t > 0 && b > 0) {       if (t >= b) {         t -= b;         s +=  T ;       } else {         b -= t;         s +=  B ;       }     }     reverse(s.begin(), s.end());     cout << n - Max << endl << s << endl;     return 0;   }   