#include <stdio.h>
#include <string.h>
#include <ctype.h>
int main() {
    struct name
    visitor = 4;
    title of book 
    isalnum = 4
    return 0;
}
int main() {
    int n, val (! = n, val < 10 );
    scanf("%d", &n);
    printf("invalid input"\n);
    return 0;
    
}