#include <bits/stdc++.h>   using namespace std;   const double PI = acos(-1.0);   const long long INFLL = 0x3f3f3f3f3f3f3f3fll;   const int maxn = 2e5 + 5;   const int mod = 1e9 + 7;   int n, k;   char ans[55][3];   int main() {     cin >> n >> k;     char ch1 =  A , ch2 =  a ;     for (int i = 0; i < n - k + 1; i++) {       string s;       cin >> s;       if (i == 0) {         if (s ==  YES ) {           for (int j = i; j < i + k; j++) {             ans[j][0] = ch1;             ans[j][1] = ch2++;             if (ch2 >  z ) ch1 =  B , ch2 =  a ;           }         } else {           ans[i][0] = ans[i + k - 1][0] = ch1;           ans[i][1] = ans[i + k - 1][1] = ch2++;           for (int j = i + 1; j < i + k - 1; j++) {             ans[j][0] = ch1;             ans[j][1] = ch2++;             if (ch2 >  z ) ch1 =  B , ch2 =  a ;           }         }       } else {         if (s ==  YES ) {           ans[i + k - 1][0] = ch1;           ans[i + k - 1][1] = ch2++;         } else {           ans[i + k - 1][0] = ans[i][0];           ans[i + k - 1][1] = ans[i][1];         }         if (ch2 >  z ) ch1 =  B , ch2 =  a ;       }     }     for (int i = 0; i < n; i++) {       cout << ans[i][0] << ans[i][1] <<    ;     }     cout << endl;     return 0;   }   