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

int main() {
    char str[7];
    int i;
    int flag=1;

    puts("Enter six digits without any space...");
    gets(str);

    for(i; i<6; i++) {
        if(isdigit(str[i])==0) {
            flag=0;
        }else if(ispunct(str[i])) {
            printf("Punctuation found \n");
        }else if(isspace(str[i])) {
            printf("Space found \n");
        }else if(isalpha(str[i])) {
            printf("Letter found %c \n", toupper(str[i]));
        }
    }

    (flag) ? puts("Entry valid") : puts("Entry invalid");
    printf("%d", flag);

    return 0;
}