For Tinkoff

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <stack>
#include <iomanip>
#include <fstream>
#include <string>
#include <set>
#include <deque>
#include <queue>
#include <map>
#include <bitset>
#include <random>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define endl "\n"
#define sqrt sqrtl

#define all(a) a.begin(), a.end();

const ll inf = 1e9 + 13;
long double eps = 1e-6;
const ll maxsz = 1e6 + 5;
ll mod = 1e9 + 7;

vector <short> dfs(vector <set <short> >& g, short v, vector <bool>& u, vector <vector <bool> > &a) {
    u[v] = true;
    short i, j;
    vector <short> n;
    for (auto i = g[v].begin(); i != g[v].end(); i++) {
        j = *i;
        if (!u[j]) {
            vector <short> x = dfs(g, j, u, a);
            for (int y = 0; y < x.size(); y++) {
                n.push_back(x[y]);
            }
            n.push_back(j);
        }
    }
    for (i = 0; i < n.size(); i++) {
        //cout << n[i] << " ";
        a[v][n[i]] = 1;
    }
    //cout << endl;
    return n;
}

signed main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    short n;
    cin >> n;
    short i, j, c1 = 0, c2 = 0;
    vector <set <short> > gr(n), gb(n);
    for (i = 0; i < n - 1; i++) {
        string s;
        cin >> s;
        for (j = 0; j < s.size(); j++) {
            if (s[j] == 'R') {
                c1++;
                gr[i].insert(j + i + 1);
                //gr[j + 1 + i].push_back(i);
            }
            else {
                c2++;
                gb[i].insert(j + i + 1);
                //gb[j + 1 + i].push_back(i);
            }
        }
    }
    vector <vector <bool> > a(n, vector <bool>(n));
    vector <vector <bool> > b(n, vector <bool>(n));
    vector <bool> u1(n);
    vector <bool> u2(n);
    for (i = 0; i < n; i++) {
        if (!u1[i]) {
            vector <short> gg = dfs(gr, i, u1, a);
        }
    }
    for (i = 0; i < n; i++) {
        if (!u2[i]) {
            vector <short> gg = dfs(gb, i, u2, b);
        }
    }
    for (i = 0; i < n; i++) {
        for (j = i + 1; j < n; j++) {
            if (a[i][j] == 1 && b[i][j] == 1) {
                cout << "NO" << endl;
                return 0;
            }
        }
    }
    cout << "YES" << endl;
    return 0;
}