#include <bits/stdc++.h>   using namespace std;   const int MOD = 1e9 + 7;   const long long int INF = 1e12;   int n, k;   int memo[101][101][101];   int solve(string &str, int i, int N, int _max) {     _max = max(N, _max);     int &a = memo[i][N][_max];     if (a != -1) return a;     if (i == n) return a = (_max == k);     if (str[i] !=  N ) {       bool temp1 = solve(str, i + 1, 0, _max);       if (str[i] ==  Y  || temp1) return a = temp1;     }     return a = solve(str, i + 1, N + 1, _max);   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     memset(memo, -1, sizeof(memo));     cin >> n >> k;     string str;     cin >> str;     cout << (solve(str, 0, 0, 0) ?  YES  :  NO );     return 0;   }   