Untitled

#include <iostream>
using namespace std;
int main()
{
    char mas[100][100];
    int n, m;
    cin >> n >> m;
    int y = 0;
    for (int i = 0; i < n; i++)
    {
        for (int w = 0; w < m; w++)
        {
            if (y % 2 != 0)
            {
                cout << "* ";
            }
            else
            {
                cout << ". ";
            }
            y++;
        }
        cout << "\n";
    }
}