func_code_string: #include <bits/stdc++.h>   template <class T>   const T& min(const T& a, const T& b, const T& c) {     return min(a, min(b, c));   }   template <class T>   const T& max(const T& a, const T& b, const T& c) {     return max(a, max(b, c));   }   using namespace std;   int gcd(long long a, long long b) {     while (true) {       if (a < b) swap(a, b);       if (b == 0) return a;       a = a % b;     }   }   int main() {     int n, k;     cin >> n >> k;     if (k > n) {       cout <<  -1 ;       return 0;     }     if (k == 1) {       if (n == 1)         cout <<  a ;       else         cout <<  -1 ;       return 0;     }     if (k == 2) {       for (__typeof(n) i = 0; i < n; i++) {         cout << (((i % 2) == 0) ?  a  :  b );       }       return 0;     }     int written = 0;     for (__typeof(n - (k - 2)) i = 0; i < n - (k - 2); i++) {       cout << (((i % 2) == 0) ?  a  :  b );     }     for (__typeof(k - 2) i = 0; i < k - 2; i++) {       char c =  c  + i;       cout << c;     }   }   template <class T>   string toStr(T t) {     std::stringstream strstream;     string resStr;     strstream << t;     strstream >> resStr;     return resStr;   }   