def solution(n, graph):
    start = 0
    end = n - 1

    def dfs(s):
        visited = [0] * n

        def _dfs(s):
            visited[s] = 1
            for v in graph[s]:
                if not visited[v]:
                    _dfs(v)
        _dfs(s)
        return visited

    d1 = dfs(start)[end]
    d2 = dfs(end)[start]
    return d1 == d2 == 1


n = int(input())
graph = [[] for _ in range(n)]
for i in range(n-1):
    tmp = input()
    for j, c in enumerate(tmp, i+1):
        if c == 'R':
            graph[j].append(i)
        else:
            graph[i].append(j)
if solution(n, graph):
    print('NO')
else:
    print('YES')