E

#include <algorithm>
#include <iostream>
#include <array>
#include <vector>
#include <numeric>
#include <random>
#include <chrono>
#include <set>
#include <map>
#include <queue>

#define int long long
using namespace std;

const long long INF = 1e9 + 7;
const int MAXN = 1e5 + 1000;
const int N = 1e5 + 10;

vector<vector<pair<int, int>>> g;
vector<vector<int>> tree;
array<int, MAXN> used, tin, up, color;
int timer = 0;
set<int> bridge;
map<int, pair<int, int>> decompress;

void dfs(int v, int e = -1) {
    used[v] = true;
    tin[v] = up[v] = timer++;
    for (auto [to, num]: g[v]) {
        if (num == e) {
            continue;
        }
        if (used[to]) {
            up[v] = min(up[v], tin[to]);
        } else {
            dfs(to, num);
            up[v] = min(up[v], up[to]);
            if (up[to] > tin[v]) {
                bridge.insert(num);
            }
        }
    }
}

int col = 0;

void paint(int v) {
    used[v] = true;
    color[v] = col;
    for (auto [to, num]: g[v]) {
        if (bridge.contains(num)) {
            continue;
        }
        if (!used[to]) {
            paint(to);
        }
    }
}

inline void solve() {
    int n, m;
    cin >> n >> m;
    g.clear();
    g.resize(n);
    for (int i = 0; i < m; ++i) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        g[u].emplace_back(v, i);
        g[v].emplace_back(u, i);
        decompress[i] = {u, v};
    }

    used.fill(0); // нахождение мостов
    tin.fill(0);
    up.fill(0);
    bridge.clear();
    timer = 0;
    for (int i = 0; i < n; ++i) {
        if (!used[i]) {
            dfs(i);
        }
    }

    used.fill(0); // раскраска компонент без мостов
    color.fill(0);
    col = 0;
    for (int i = 0; i < n; ++i) {
        if (!used[i]) {
            paint(i);
            ++col;
        }
    }

    tree.clear(); // построение дерева
    tree.resize(n);
    for (auto& i: bridge) {
        auto [u, v] = decompress[i];
        u = color[u];
        v = color[v];
        tree[u].emplace_back(v);
        tree[v].emplace_back(u);
    }

    vector<int> d(col, -1);
    queue<int> q;
    d[0] = 0;
    q.push(0);
    int max_dist = 0;
    while (!q.empty()) {
        int v = q.front();
        q.pop();
        for (auto to: tree[v]) {
            if (d[to] == -1) {
                d[to] = d[v] + 1;
                q.push(to);
            }
            if (d[to] > d[max_dist]) {
                max_dist = to;
            }
        }
    }

    fill(d.begin(), d.end(), -1);
    int start = max_dist;
    d[start] = 0;
    q.push(start);
    while (!q.empty()) {
        int v = q.front();
        q.pop();
        for (auto to: tree[v]) {
            if (d[to] == -1) {
                d[to] = d[v] + 1;
                q.push(to);
            }
            if (d[to] > d[max_dist]) {
                max_dist = to;
            }
        }
    }

    cout << bridge.size() - d[max_dist] << '\n';
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int tt = 1;
    cin >> tt;
    while (tt--) {
        solve();
    }
}