#include <iostream>
using namespace std;

bool isVowel(char x);

int main() {
    char c;
    cout << "Input a letter: ";
    cin >> c;
    cout << endl;
    if (isVowel(c)) cout << c << " is a vowel.";
    cin >> c;
    return 0;
}

bool isVowel(char x) {
     if (x == 'a'|'e'|'i'|'o'|'u') return true;
     
     return false;
}