#include <bits/stdc++.h>
#define gc()(xS==xTT&&(xTT=(xS=xB)+fread(xB,1,1<<20,stdin),xS==xTT)?0:*xS++)
#define pc(x) (p3-obuf<1000000)?(*p3++=x):(fwrite(obuf,p3-obuf,1,stdout),p3=obuf,*p3++=x)
using namespace std;
typedef long long ll;
typedef double db;
typedef long double ld;
typedef unsigned long long ull;
typedef unsigned int ui;
char xch, xB[1 << 20], *xS = xB, *xTT = xB, obuf[1000000], *p3 = obuf;
inline ll read() {
    char ch = gc();
    ll x = 0, f = 1;

    while (ch < '0' || ch > '9') {
        if (ch == '-')
            f = -1;

        ch = gc();
    }

    while ('0' <= ch && ch <= '9') {
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = gc();
    }

    return x * f;
}
static char cc[20];
template<typename item>inline void pt(register item x) {
    register int len = 0;

    if (!x)
        pc('0');

    if (x < 0)
        x = -x, pc('-');

    while (x)
        cc[len++] = x % 10 + '0', x /= 10;

    while (len--)
        pc(cc[len]);
}
inline void pS(string s) {
    for (int i = 0; i < s.length(); i++)
        pc(s[i]);
}
inline ll read2() {
    char ch = gc();
    ll x = 0, f = 1;

    while (ch < '0' || ch > '1') {
        if (ch == '-')
            f = -1;

        ch = gc();
    }

    while ('0' <= ch && ch <= '9') {
        x = (x << 1) + (ch ^ 48);
        ch = gc();
    }

    return x * f;
}
const int maxn = 55, maxm = 410, maxc = 1e6;
int n, m, a[maxn][maxm], p[maxn], top[maxn], cz[maxc][2], cnt;
void ac(int x, int y) {
    cz[++cnt][0] = x, cz[cnt][1] = y;
    top[y]++, a[y][top[y]] = a[x][top[x]], top[x]--;
}
int main() {
    n = read(), m = read();

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            top[i]++, a[i][j] = read();

    for (int i = 1; i <= n + 1; i++)
        p[i] = i;

    while (n >= 3) {
        int tot = 0;

        for (int i = 1; i <= m; i++)
            if (a[p[1]][i] == n)
                tot++;

        for (int i = 1; i <= tot; i++)
            ac(p[n], p[n + 1]);

        for (int i = m; i; i--)
            if (a[p[1]][i] == n)
                ac(p[1], p[n]);
            else
                ac(p[1], p[n + 1]);

        while (top[p[n + 1]] && a[p[n + 1]][top[p[n + 1]]] != n)
            ac(p[n + 1], p[1]);

        for (int i = m; i; i--)
            if (a[p[2]][i] != n && top[p[1]] < m)
                ac(p[2], p[1]);
            else
                ac(p[2], p[n + 1]);

        swap(p[2], p[n + 1]), swap(p[1], p[n]);

        for (int t = 1; t < n; t++) {
            tot = 0;

            for (int i = 1; i <= m; i++)
                if (a[p[t]][i] == n)
                    tot++;

            for (int i = 1; i <= tot; i++)
                ac(p[n], p[n + 1]);

            for (int i = m; i; i--)
                if (a[p[t]][i] == n)
                    ac(p[t], p[n]);
                else
                    ac(p[t], p[n + 1]);

            swap(p[n], p[n + 1]), swap(p[n + 1], p[t]);
        }

        for (int i = 1; i < n; i++) {
            while (top[p[i]] && a[p[i]][top[p[i]]] == n)
                ac(p[i], p[n + 1]);

            while (top[p[i]] < m)
                ac(p[n], p[i]);
        }

        n--;
    }

    for (int _ = 1; _ <= 2; _++) {
        int tot = 0;

        for (int i = 1; i <= m; i++)
            if (a[p[1]][i] == 1)
                tot++;

        for (int i = 1; i <= tot; i++)
            ac(p[2], p[3]);

        for (int i = m; i; i--)
            if (a[p[1]][i] == 1)
                ac(p[1], p[2]);
            else
                ac(p[1], p[3]);

        for (int i = 1; i <= m - tot; i++)
            ac(p[3], p[1]);

        for (int i = 1; i <= tot; i++)
            ac(p[2], p[1]);

        for (int i = 1; i <= tot; i++)
            ac(p[3], p[2]);

        swap(p[1], p[2]);
    }

    for (int i = m; i && a[p[1]][i] == 1; i--)
        ac(p[1], p[3]);

    for (int i = m; i && a[p[2]][i] == 1; i--)
        ac(p[2], p[3]);

    while (top[p[1]])
        ac(p[1], p[2]);

    pt(cnt);

    for (int i = 1; i <= cnt; i++)
        pc('\n'), pt(cz[i][0]), pc(' '), pt(cz[i][1]);

    fwrite(obuf, p3 - obuf, 1, stdout);
    return 0;
}