#include <bits/stdc++.h>
#define int long long
#define double long double
#define Task ""
#define READFILE freopen(Task".inp", "r", stdin)
#define WRITEFILE freopen(Task".out", "w", stdout)
#define oo 1e18
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define watch(x) cout << (#x) << " = " << x << endl
#define debug(x) cout << (#x) << " = " << x << endl
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define endl '\n'
#define max3(a,b,c) max(max(a, b), c)
#define max4(a,b,c,d) max(max(a, b), max(c, d))
#define min4(a,b,c,d) min(min(a, b), min(c, d))
#define debug4(a,b,c,d) watch(a);watch(b);watch(c);watch(d)
#define ever (;true;)
#define maxn 505

#define PI 3.14159265

using namespace std;

typedef pair < int, int > ii;
typedef pair < int, ii > iii;
typedef pair < ii, ii > iiii;
typedef vector < int > vi;
typedef vector < ii > vii;
typedef vector < vi > vvi;
typedef vector < iii > viii;
typedef vector < vii > vvii;
typedef vector < iiii > viiii;
typedef vector < vvi > vvvi;

void init(){
    FAST;
    if (fopen(Task".inp", "r")){
        READFILE;
        WRITEFILE;
    }
}

const int N = 1e3 + 5;

int color[N][N];
bool colored[N][N];
const int dx[] = {0, 0, 1, 1};
const int dy[] = {0, 1, 0, 1};

void Run_case(){
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; ++i){
        for (int j = 0; j < m; ++j){
            cin >> color[i][j];
        }
    }
    vector < iii > res;
    memset(colored, 0, sizeof(colored));
    auto ok = [&](ii x) -> int{
        if (x.fi < 0 || x.fi > n - 2 || x.se < 0 || x.se > m - 2)
            return 0;
        set < int > Set;
        for (int dir = 0; dir < 4; ++dir){
            int X = x.fi + dx[dir], Y = x.se + dy[dir];
            if (!colored[X][Y]){
                Set.insert(color[X][Y]);
            }
        }
        if (Set.size() == 0 || Set.size() > 1) return 0;
        for (int dir = 0; dir < 4; ++dir){
            int X = x.fi + dx[dir], Y = x.se + dy[dir];
            colored[X][Y] = 1;
        }
        return *Set.begin();
    };
    queue < ii > q;
    for (int i = 0; i < n - 1; ++i){
        for (int j = 0; j < m - 1; ++j){
            int cur = ok(ii(i, j));
            if (cur != 0){
                res.pb(iii(cur, ii(i, j)));
                q.push(ii(i, j));
            }
        }
    }
    while (q.size()){
        ii u = q.front();
        q.pop();
        for (int DX = -1; DX < 2; DX++){
            for (int DY = -1; DY < 2; DY++){
                if (DX == 0 && DY == 0) continue;
                ii v = ii(u.fi + DX, u.se + DY);
                if (v.fi < 0 || v.fi > n - 2 || v.se < 0 || v.se > m - 2)
                    continue;
                int cur = ok(v);
                if (cur != 0){
                    q.push(v);
                    res.pb(iii(cur, v));
                }
            }
        }
    }
    for (int i = 0; i < n; ++i){
        for (int j = 0; j < m; ++j){
            if (!colored[i][j]){
                cout << -1 << endl;
                return;
            }
        }
    }
    cout << res.size() << endl;
    for (int i = (int)res.size() - 1; i >= 0; --i)
    //for (int i = 0; i < (int)res.size(); ++i)
    {
        cout << res[i].se.fi + 1 << ' ' << res[i].se.se + 1 << ' '
        << res[i].fi << endl;
    }
}

void check(){
    ifstream fi(".inp"), fo(".out");
    int n, m;
    fi >> n >> m;
    int a[n][m];
    for (int i = 0; i < n; ++i){
        for (int j = 0; j < m; ++j){
            fi >> a[i][j];
        }
    }
    fi.close();
    int k;
    fo >> k;
    int b[n][m];
    memset(b, 0, sizeof(b));
    while (k--){
        int x, y, c;
        fo >> x >> y >> c;
        x--;
        y--;
        b[x][y] = c;
        b[x+1][y] = c;
        b[x][y+1] = c;
        b[x+1][y+1] = c;
        cerr << x << ' ' << y << ' ' << c << endl;
        for (int i = 0; i < n; ++i){
            for (int j = 0; j < m; ++j){
                cerr << b[i][j] << ' ';
            }
            cerr << endl;
        }
        cerr << endl;
    }
    fo.close();
    bool ok = 1;
    for (int i = 0; i < n && ok; ++i){
        for (int j = 0; j < m && ok; ++j){
            if (a[i][j] != b[i][j]) ok = 0;
        }
    }
    if (ok) cerr << "AC";
    else cerr << "WA";
    exit(0);
}

signed main(){
    #ifndef ONLINE_JUDGE
    check();
    #endif // ONLINE_JUDGE
    init();
    int t = 1;
    //cin >> t;
    while (t--){
        Run_case();
    }
    return 0;
}