#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int T;
    if (!(cin >> T)) return 0;
    while (T--) {
        int n;
        cin >> n;
        vector<string> s(n);
        for (int i = 0; i < n; ++i) cin >> s[i];

        bool ok = true;
        for (int i = 0; i < n && ok; ++i) {
            if (s[i][i] != '1') ok = false;
            for (int j = i + 1; j < n; ++j)
                if (s[i][j] == '1' && s[j][i] == '1') ok = false;
        }
        if (!ok) {
            cout << "No\n";
            continue;
        }

        // descendants lists
        vector<vector<int>> desc(n);
        vector<int> cnt(n);
        for (int i = 0; i < n; ++i) {
            int c = 0;
            for (int j = 0; j < n; ++j)
                if (s[i][j] == '1') ++c;
            cnt[i] = c;
        }
        for (int i = 0; i < n; ++i) desc[i].reserve(cnt[i]);
        for (int i = 0; i < n; ++i)
            for (int j = 0; j < n; ++j)
                if (s[i][j] == '1') desc[i].push_back(j);

        // topological order: if u reaches v, then |Desc(v)| < |Desc(u)|
        vector<int> order(n);
        iota(order.begin(), order.end(), 0);
        sort(order.begin(), order.end(),
             [&](int a, int b) { return cnt[a] > cnt[b]; });

        vector<int> seen(n, 0);
        vector<pair<int,int>> edges;
        edges.reserve(n - 1);

        for (int i = 0; i < n && (int)edges.size() < n; ++i) {
            int cur = i + 1;
            seen[i] = cur;                     // i itself is not a child of i
            for (int v : order) {
                if (s[i][v] != '1' || seen[v] == cur) continue;
                edges.emplace_back(i, v);
                if ((int)edges.size() >= n) break;
                for (int w : desc[v]) seen[w] = cur;
            }
        }

        if ((int)edges.size() != n - 1) {
            cout << "No\n";
            continue;
        }

        vector<vector<int>> out(n), und(n);
        for (auto [x, y] : edges) {
            out[x].push_back(y);
            und[x].push_back(y);
            und[y].push_back(x);
        }

        // check connectedness
        vector<char> vis(n, 0);
        vector<int> st;
        st.reserve(n);
        st.push_back(0);
        vis[0] = 1;
        int visited = 0;
        while (!st.empty()) {
            int u = st.back(); st.pop_back();
            ++visited;
            for (int w : und[u])
                if (!vis[w]) {
                    vis[w] = 1;
                    st.push_back(w);
                }
        }
        if (visited != n) {
            cout << "No\n";
            continue;
        }

        // verify reachability
        vector<char> reach(n);
        for (int u = 0; u < n && ok; ++u) {
            fill(reach.begin(), reach.end(), 0);
            vector<int> stack;
            stack.reserve(n);
            stack.push_back(u);
            reach[u] = 1;
            while (!stack.empty()) {
                int x = stack.back(); stack.pop_back();
                for (int y : out[x])
                    if (!reach[y]) {
                        reach[y] = 1;
                        stack.push_back(y);
                    }
            }
            for (int v = 0; v < n; ++v)
                if ((s[u][v] == '1') != reach[v]) {
                    ok = false;
                    break;
                }
        }

        if (!ok) {
            cout << "No\n";
            continue;
        }

        cout << "Yes\n";
        for (auto [x, y] : edges)
            cout << x + 1 << ' ' << y + 1 << '\n';
    }
    return 0;
}