#include <iostream>
#include <algorithm>
#include <cstdio>
#include <array>
#include <vector>
#include <bitset>
#define pii pair <int, int>
using namespace std;
#ifdef ONLINE_JUDGE

/* #define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1 << 21, stdin), p1 == p2) ? EOF : *p1++) */
/* char buf[1 << 23], *p1 = buf, *p2 = buf, ubuf[1 << 23], *u = ubuf; */

#endif
int read() {
    int p = 0, flg = 1;
    char c = getchar();
    while (c < '0' || c > '9') {
        if (c == '-') flg = -1;
        c = getchar();
    }
    while (c >= '0' && c <= '9') {
        p = p * 10 + c - '0';
        c = getchar();
    }
    return p * flg;
}
void write(int x) {
    if (x < 0) {
        x = -x;
        putchar('-');
    }
    if (x > 9) {
        write(x / 10);
    }
    putchar(x % 10 + '0');
}
bool _stmer;

#define fi first
#define se second

const int N = 305;

array <bitset <N>, N> vis;
array <string, N> mp;
char strbuf[N];

void solve() {
    vector <pii> ans;
    int n = read();
    vis.fill((bitset <N>)0);
    for (int i = 1; i <= n; i++) {
        scanf("%s", strbuf);
        mp[i] = strbuf, mp[i] = " " + mp[i];
        for (int j = 1; j <= n; j++)
            if (mp[i][j] == '1' && !vis[i][j]) vis[i][j] = vis[j][i] = 1, ans.push_back(make_pair(i, j));
    }
    bool _flg = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = i + 1; j <= n; j++) {
            if (mp[i][j] == '0') {
                bool flg = 0;
                for (int k = 1; k <= n; k++)
                    flg |= i != k && j != k && mp[i][k] == mp[j][k] && mp[i][k] == '1';
                if (!flg) _flg = 1;
            }
        }
    }
    if (_flg) puts("NO");
    else {
        puts("YES");
        write(ans.size()), puts("");
        for (auto k : ans) {
            write(k.fi), putchar(32);
            write(k.se), puts("");
        }
    }
}

bool _edmer;
int main() {
    cerr << (&_stmer - &_edmer) / 1024.0 / 1024.0 << "MB\n";
#ifndef cxqghzj
//    freopen("bridge.in", "r", stdin);
//    freopen("bridge.out", "w", stdout);
#endif
    int T = read();
    while (T--) solve();
    return 0;
}