func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int a[300], ans[500][2], tot, v[300];   void sl(int p, int x) {     if (p == x || x == 0) return;     if (a[x] == 0 || a[x] == x) {       ans[tot][0] = p, ans[tot][1] = x;       a[x] = x;       a[p] = 0;       tot++;       return;     }     if (v[x]) {       ans[tot][0] = p, ans[tot][1] = n;       a[p] = 0;       a[n] = x;       tot++;       return;     }     v[p] = 1;     sl(x, a[x]);     ans[tot][0] = p, ans[tot][1] = x;     a[x] = x;     a[p] = 0;     tot++;     v[p] = 0;   }   int main() {     scanf( %d%d , &n, &m);     int p = 0, t, sum = 0;     for (int i = 0; i < m; i++) {       scanf( %d , &t);       sum += t;       while (t--) {         int x;         scanf( %d , &x);         a[x] = ++p;       }     }     for (int i = n; i > 0; i--) {       sl(i, a[i]);       sl(n, a[n]);     }     printf( %d n , tot);     for (int i = 0; i < tot; i++) {       printf( %d %d n , ans[i][0], ans[i][1]);     }   }   