#include <bits/stdc++.h>

int main() {
  using namespace std;
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector a(n, vector<int>(n, -1));
  a[0][0] = 1;
  a[n - 1][n - 1] = 1;
  auto query = [&](int i, int j) -> bool {
    cout << i + 1 << ' ' << j + 1 << endl;
    if (a[i][j] != -1) return a[i][j];
    string s;
    cin >> s;
    return (a[i][j] = s[0] == 'b');
  };
  constexpr array di{1, 0, -1, 0};
  constexpr array dj{0, 1, 0, -1};
  vector visited(n, vector<bool>(n));
  auto dfs = [&](auto self, int i, int j) -> void {
    if (i == n - 1 && j == n - 1) {
      cout << "Yes" << endl;
      exit(0);
    }
    for (int d : {0, 1, 2, 3}) {
      int ni = i + di[d];
      int nj = j + dj[d];
      if (min(ni, nj) < 0 || max(ni, nj) >= n || !query(ni, nj)) continue;
      if (visited[ni][nj]) continue;
      visited[ni][nj] = true;
      self(self, ni, nj);
    }
  };
  visited[0][0] = true;
  dfs(dfs, 0, 0);
  cout << "No" << endl;
}