#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int MAXN = 1001;
const int MAXM = 200'001;
const int INF = 1e8;

vector<pair<int, int>> g[MAXN];
vector<int> g2[MAXN];
int vis[MAXN], vis2[MAXM], vis3[MAXN];
int nodes, edges, fok[MAXN], ans[MAXN][MAXN], timer = 2, timer2 = INF, st;

void dfs(int u, int p = -1) {
    vis[u] = true;
    nodes++;
    for (auto [v, idx] : g[u]) {
        if (v == p) continue;
        if (vis2[idx] == 0) {
            vis2[idx] = true;
            edges++;
        }
        if (!vis[v]) {
            vis2[idx] = 3;
            dfs(v, u);
        } else {
            st = u;
            ans[u][v] = ans[v][u] = 1;
        }
    }
}

vector<int> cyc;
vector<int> res;

void dfs2(int u, int p = -1) {
    vis3[u] = true;
    cyc.push_back(u);
    for (auto [v, idx] : g[u]) {
        if (v == p) continue;
        if (v == st) {
            res = cyc;
        }
        if (!res.empty()) return;
        if (!vis3[v]) {
            dfs2(v, u);
        }
        if (!res.empty()) return;
    }
    cyc.pop_back();
}

void dfs3(int u)  {
    vis3[u] = true;
    for (auto [v, idx] : g[u]) {
        if (!vis3[v]) {
            ans[u][v] = ans[v][u] = timer++;
        }
    }
    for (auto [v, idx] : g[u]) {
        if (!vis3[v]) {
            dfs3(v);
        }
    }
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    int n, m; cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            ans[i][j] = timer2--;
        }
    }
    for (int i = 0; i < m; i++) {
        int u, v; cin >> u >> v;
        g[u].emplace_back(v, i);
        g[v].emplace_back(u, i);
    }
    for (int i = 1; i <= n; i++) {
        if (g[i].empty()) {
            cout << "-1\n";
            return 0;
        }
    }
    for (int i = 1; i <= n; i++) {
        if (!vis[i]) {
            nodes = edges = 0;
            st = i;
            dfs(i);
            if (edges > nodes) {
                cout << "-1\n";
                return 0;
            }
            fill(vis3, vis3+MAXN, false);
            cyc.clear(); res.clear();
            dfs2(st);
            if (edges == nodes && res.empty()) {
                throw 1;
            }
            if (edges == nodes - 1 && !res.empty()) throw 1;
            if (res.empty()) {
                fill(vis3, vis3+MAXN, false);
                dfs3(st);
            } else {
                for (int i = 1; i < res.size(); i++) {
                    ans[res[i-1]][res[i]] = ans[res[i]][res[i-1]] = timer++;
                }
                ans[res[0]][res.back()] = ans[res.back()][res[0]] = timer++;
                fill(vis3, vis3+MAXN, false);
                for (int u : res) vis3[u] = true;
                for (int u : res) {
                    dfs3(u);
                }
            }
        }
    }
    
    for (int i = 1; i <= n; i++) {
        for (int j = i+1; j <= n; j++) {
            cout << ans[i][j] << " ";
        }
        cout << "\n";
    }
    return 0;
}