6.3.9

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <cmath>

using namespace std;

int main()
{
    int n, t, m;
    t = 0;
    cin >> n >> m;
    int **a = new int *[n];
    for (int i = 0; i < n; i++) {
        a[i] = new int[m];
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> *(*(a + i) + j);
        }
    }
    int *b;
    if (n % 2 == 0) {
        for (int i = 0; i < n; i+=2) {
            b = a[i];
            a[i] = a[i+1];
            a[i+1] = b;
        }
    }

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cout << a[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}