HA32_Colored(15)

#include <iostream>
#include <vector>
#include <bitset>

using namespace std;

const int N_MAX = 5000;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int N;
    cin >> N;
    vector<string> edges(N - 1);

    for (int i = 0; i < N - 1; i++) {
        cin >> edges[i];
    }

    vector<vector<int>> red_adj(N);
    vector<vector<int>> blue_adj(N);

    for (int i = 0; i < N - 1; i++) {
        for (int j = 0; j < edges[i].size(); j++) {
            int neighbor = i + 1 + j;
            if (edges[i][j] == 'R') {
                red_adj[i].push_back(neighbor);
            } else if (edges[i][j] == 'B') {
                blue_adj[i].push_back(neighbor);
            }
        }
    }

    vector<bitset<N_MAX>> reach_red(N);
    vector<bitset<N_MAX>> reach_blue(N);

    for (int i = 0; i < N; i++) {
        reach_red[i].set(i);
        reach_blue[i].set(i);
    }

    for (int A = 0; A < N; A++) {
        for (int B : red_adj[A]) {
            reach_red[B] |= reach_red[A];
        }
        for (int B : blue_adj[A]) {
            reach_blue[B] |= reach_blue[A];
        }
    }

    for (int B = 0; B < N; B++) {
        bitset<N_MAX> intersection = reach_red[B] & reach_blue[B];
        intersection[B] = 0; // Exclude B itself
        if (intersection.any()) {
            cout << "NO" << endl;
            return 0;
        }
    }

    cout << "YES" << endl;
    return 0;
}