gcj r2 no trust p1

for(int i = 1; i<=n; i++){
        for(int j = 1; j<=n; j++){

            if((arr[i][j] - 1) + abs(mid - i) + abs(mid - j) == k){
                int oi = i, oj = j;
                change.pb(arr[i][j]);
                int dx = (mid > i) ? 1 : -1;
                int dy = (mid > j) ? 1 : -1;
                if(dx + dy == 0){
                    while(i != mid){
                        //cout << i << " ";
                        /*if(arr[i][j] + 1 != arr[i+dx][j]){*/
                            change.pb(arr[i+dx][j]);
                        /*}*/
                        i += dx;
                    }
                    assert(i == mid);
                    //change.pb(arr[i][j]);
                    while(j != mid){
                        /*if(arr[i][j] + 1 != arr[i][j + dy]){*/
                            change.pb(arr[i][j+dy]);
                        /*}*/
                        j += dy;
                    }
                }else{
                    //cout << "wave\n";
                    while(j != mid){
                        //cout << j << " ";
                        /*if(arr[i][j] + 1 != arr[i][j + dy]){*/
                            change.pb(arr[i][j+dy]);
                        /*}*/
                        j += dy;
                    }
                    assert(mid == j);
                    /*change.pb(arr[i][j]);*/
                    while(i != mid){
                        /*if(arr[i][j] + 1 != arr[i+dx][j]){*/
                            change.pb(arr[i+dx][j]);
                        /*}*/
                        i += dx;
                    }
                }
                vector<int> tmp = change;
                change.clear();
                vector<pair<int, int>> ans;
                for(int i = 0; i<sz(tmp); i++){
                    int fl = 0;
                    if(i > 0 && tmp[i] != tmp[i-1]+1) ans.pb(mp(tmp[i-1], tmp[i]));
                    /*if(i < sz(tmp)-1 && tmp[i] != tmp[i+1]-1) fl++;*/
                    /*if(fl) change.pb(tmp[i]);*/
                }
                int flag = 0;
                for(const auto& [x, y] : ans){
                    if(y < x){
                        flag = 1;
                        break;
                    }
                }
                if(!flag){
                    /*cerr << oi << " " << oj << "\n";*/
                    cout << sz(ans) << "\n";
                    for(int d = 0; d<sz(ans); d++){
                        cout << ans[d].first << " " << ans[d].second << "\n";
                    }
                    return ;
                }
                change.clear();
                i = oi, j= oj;
            }
        }
    }