#include <stdio.h>
//#include <string.h>

int main() {
    int w, h, i, j, bool = 0;

    while (1) {
        scanf("%d %d", &h, &w);

        if (w == 0 && h == 0)
            break;

        bool = 1;

        for (i = 0; i < h; ++i) {
            for (j = 0; j < w; ++j) {
                if (bool) {
                    printf("#");
                    bool = 0;
                } else {
                    printf(".");
                    bool = 1;
                }
            }
            bool = !bool;
            printf("\n");
        }
        printf("\n");
    }

    return 0;
}
