int main() {
    int i, j, ms = 250;    
    const char *a = ;
    time_t start, now;
    struct timespec delay;
    delay.tv_sec = 0;
    delay.tv_nsec = ms * 1000000L;
    printf();  
    time(&start);
    while(1) {
        for (i = 0; i < 4; i++) {
            printf();          
            printf();        
            for (j = 0; j < 80; j++) {  
                printf(, a[i]);
            }
            fflush(stdout);
            nanosleep(&delay, NULL);
        }
        
        time(&now);
        if (difftime(now, start) >= 20) break;
    }
    printf(); 
    return 0;
}