int lesson1()
{
    int n, k;
    cin >> n >> k;
    char* row[1000];
    for (int i = 0; i < n; i++) {
        *(row + i) = "I";
    }
    for (int i = 0; i < k; i++) {
        int l, r;
        cin >> l >> r;
        for (int j = l - 1; j < r; j++) {
            row[j] = ".";
        }
    }
    for (int i = 0; i < n; i++) {
        cout << row[i];
    }
    return 0;
}