func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, a, b;   int tmp[33][33];   int source[33][33];   int target[33][33];   pair<int, int> prv[33][33];   bool block[33][33];   vector<pair<int, int> > R;   int dx[] = {-1, -1, -1, 0, 0, 1, 1, 1};   int dy[] = {-1, 0, 1, -1, 1, -1, 0, 1};   void save() {     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j) tmp[i][j] = source[i][j];   }   void load() {     R.clear();     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j) source[i][j] = tmp[i][j];   }   void check() {     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j)         if (source[i][j] != target[i][j]) return;     printf( %d n , (int)R.size() - 1);     for (pair<int, int> r : R) printf( %d %d n , r.first + 1, r.second + 1);     exit(0);   }   void make(int first, int second) {     swap(source[R.back().first][R.back().second], source[first][second]);     R.push_back(pair<int, int>(first, second));     a = first;     b = second;   }   bool in(int first, int second) {     return 0 <= first && first < n && 0 <= second && second < m &&            !block[first][second];   }   void path(int first, int second) {     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j) prv[i][j] = pair<int, int>(-1, -1);     queue<pair<int, int> > Q;     Q.push(pair<int, int>(a, b));     pair<int, int> c = pair<int, int>(first, second);     while (!Q.empty()) {       first = Q.front().first;       second = Q.front().second;       Q.pop();       for (int d = (0); d < (8); ++d) {         int nx = first + dx[d];         int ny = second + dy[d];         if (in(nx, ny) && prv[nx][ny] == pair<int, int>(-1, -1)) {           prv[nx][ny] = pair<int, int>(first, second);           Q.push(pair<int, int>(nx, ny));         }       }     }     stack<pair<int, int> > S;     while (c != pair<int, int>(a, b)) {       S.push(c);       c = prv[c.first][c.second];     }     while (!S.empty()) {       make(S.top().first, S.top().second);       S.pop();     }   }   void setp(int i, int j) {     path(i, j);     pair<int, int> s = pair<int, int>(i, j);     block[i][j] = 1;     for (int p = (0); p < (n); ++p)       for (int q = (0); q < (m); ++q)         if (!block[p][q] && source[p][q] == target[i][j])           s = pair<int, int>(p, q);     block[i][j] = 0;     if (s == pair<int, int>(i, j)) {       printf( -1 n );       exit(0);     }     for (;;) {       path(s.first, s.second);       s = R[R.size() - 2];       if (pair<int, int>(i, j) == s) break;       block[s.first][s.second] = 1;       path(i, j);       block[s.first][s.second] = 0;     }     block[i][j] = 1;   }   int main() {     scanf( %d %d , &n, &m);     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j) scanf( %d , &source[i][j]);     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j) scanf( %d , &target[i][j]);     save();     if (n == 1 || m == 1) {       for (int s = (0); s < (max(n, m)); ++s) {         for (int d = -1; d <= 1; d += 2) {           load();           R.push_back(pair<int, int>(n == 1 ? 0 : s, n == 1 ? s : 0));           for (int i = s + d; - 1 < i && i < max(n, m); i += d) {             make(n == 1 ? 0 : i, n == 1 ? i : 0);             check();           }         }       }       printf( -1 n );       return 0;     }     for (int i = (0); i < (n); ++i)       for (int j = (0); j < (m); ++j)         if (source[i][j] == target[n - 1][m - 1]) a = i, b = j;     R.push_back(pair<int, int>(a, b));     for (int i = (0); i < (n - 2); ++i)       for (int j = (0); j < (m); ++j) setp(i, j);     for (int j = (0); j < (m - 1); ++j) {       setp(n - 2, j);       setp(n - 1, j);     }     check();     if (a == n - 1)       make(a - 1, b);     else       make(a + 1, b);     check();     printf( -1 n );     return 0;   }   