#include <bits/stdc++.h>
#define all(x)  (x).begin(), (x).end()
#define allr(x) (x).rbegin(), (x).rend()
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;

int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int t;
	cin >> t;
	while (t--) {
		int n;
		cin >> n;
		vector<string> vs(n);
		for (int i = 0; i < n; i++)
			cin >> vs[i];
		vector<pii> ans;
		for (int i = 0; i < n; i++)
			for (int j = i + 1; j < n; j++)
				if (vs[i][j] == '1')
					ans.push_back(pii(i + 1, j + 1));

		bool ok = 1;
		for (int i = 0; i < n; i++)
			for (int j = i + 1; j < n; j++)
				if (vs[i][j] == '0') {
					bool mok = 0;
					for (int k = 0; k < n; k++)
						if (vs[i][k] == '1' && vs[k][j] == '1')
							mok = 1;
					ok = (ok & mok);
				}

		if (ok) {
			cout << "YES\n";
			for (auto p : ans)
				cout << p.first << ' ' << p.second << "\n";
		} else
			cout << "NO\n";
	}

	return 0;
}