#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second

int n, m;
int d[152][152];
vector <int> v[152];
vector < pair <int, pair <int, int> > > mu;
///APDM
int wh;

void dfs(int nod)  {
    for(auto x : v[nod])  {
        if(d[wh][x] == 0 || d[wh][x] > d[wh][nod] + 1)  {
            d[wh][x] = d[wh][nod] + 1;
            dfs(x);
        }
    }
}

int main()  {
    freopen("a.in", "r", stdin);
    freopen("a.out", "w", stdout);
    cin >> n >> m;
    for(int i = 1;i <= m;i++)  {
        int x, y;
        cin >> x >> y;
        v.push_back(x), v.push_back(y);
    }
    for(int i = 1;i <= n;i++)
        wh = i, dfs(i);
    for(int i = 1;i <= n;i++)
    for(int j = 1;j <= m;j++)  {
        if(i >= j)
            continue;
        mu.push_back({d[i][j], {i, j}});
    }
    sort(mu.begin(), mu.end());
    for(int i = mu.size() - 1;i >= mu.size() - (m - (n + 1));i--)  {

    }
    return 0;
}