#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef vector<LL> VL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef double db;

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int n;
	cin >> n;
	int m = n;
	vector<string> v(n);
	FOR (i, 0, n) cin >> v[i];
	bool ok = true;
	FOR (i, 0, n)
	{
		map<char, int> cnt;
		FOR (j, 0, m)
		{
			cnt[v[i][j]]++;
			if (j + 2 < m && v[i][j] == v[i][j + 1] && v[i][j] == v[i][j + 2])
				ok = false;
		}
		if (cnt['W'] != n / 2)
			ok = false;
	}
	FOR (j, 0, m)
	{
		map<char, int> cnt;
		FOR (i, 0, n)
		{
			cnt[v[i][j]]++;
			if (i + 2 < n && v[i][j] == v[i + 1][j] && v[i + 2][j] == v[i][j])
				ok = false;
		}
		if (cnt['W'] != n / 2)
			ok = false;
	}
	cout << ok << '\n';
	
	return 0;
}