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

int count_vowels(char *str) {
    int count;
    for (int i = 0; str[i]; i++) {
        char c = tolower(str[i]);
        if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
            count++;
        } else if(!isalpha(str[i])) {
            printf("Invalid input\n");
            return -1;
        }
    }
    return count;
}
int main() {
    char input[101];
    printf("Enter a string: ");
    fgets(input, sizeof(input), stdin);
    input[strcspn(input, "\n")] = 0;
    
    int vowels = count_vowels(input);
    if (vowels != -1) {
        printf("%d\n", vowels);
    }
    return 0;
}