#include <bits/stdc++.h>

using std::cin;
using std::cout;
using std::endl;
using std::string;
using std::vector;
using ll = long long;
using vi = vector<ll>;
using vii = vector<vi>;
using pii = std::pair<ll,ll>;

#define rep(i,j,k) for(ll i=ll(j); i<ll(k); i++)
#define REP(i,j,k) for(ll i=ll(j); i<=ll(k); i++)
#define per(i,j,k) for(ll i=ll(j); i>=ll(k); i--)
#define ln "\n"
#define all(a) a.begin(),a.end()
#define pb emplace_back
#define mp std::make_pair
#define mtp std::make_tuple

int main(){
    cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    ll N,M; cin >> N >> M;
    vector<vii> data(N,vii(M));
    vi A(N*M);
    rep(i,0,N*M){
        cin >> A[i];
        A[i]--;
        data[i/M][A[i]].pb(i);
    }
    vii edge(N+M), weight(N+M);
    {
        ll cnt = N*M;
        rep(i,0,N){
            rep(j,0,M){
                if(data[i][j].size() == 0){
                    edge[j].pb(M+i);
                    weight[j].pb(cnt++);
                }
                else{
                    rep(k,1,data[i][j].size()){
                        edge[M+i].pb(j);
                        weight[M+i].pb(data[i][j][k]);
                    }
                }
            }
        }
    }
    ll ans = 0;
    {
        vector<bool> flag(N+M);
        rep(i,0,N+M){
            if(edge[i].empty()) continue;
            if(flag[i]) continue;
            flag[i] = true;
            std::queue<ll> que;
            que.push(i);
            ll sum = 0;
            while(!que.empty()){
                ll now = que.front();
                que.pop();
                sum += edge[now].size();
                for(auto next: edge[now]){
                    if(flag[next]) continue;
                    flag[next] = true;
                    que.push(next);
                }
            }
            sum /= 2;
            ans += sum+1;
        }
        cout << ans << ln;
    }
    
    vector<bool> used(N*M*2);

    vi ord;

    std::function<void(ll)> dfs = [&](ll now){
        rep(i,0,edge[now].size()){
            ll next = edge[now][i];
            ll idx = weight[now][i];
            if(used[idx]) continue;
            used[idx] = true;
            dfs(next);
            ord.pb(idx);
        }
    };

    rep(i,0,N+M){
        dfs(i);
        {
            vi nord;
            for(auto el: ord){
                if(el < N*M) nord.pb(el);
            }
            ord = nord;
        }
        if(ord.empty()) continue;
        cout << ord[0]+1 << " " << N*M+1 << ln;
        rep(j,1,ord.size()) cout << ord[j]+1 << " "<< ord[j-1]+1 << ln;
        cout << N+M+1 << " " << ord.back()+1 << ln;
        ord.clear();
    }
}