#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<unordered_set>

bool isvowel(char c){
    c=std::tolower(c);
    return (c =='a' || c =='e' || c =='o' || c =='u' );
}

bool isvalid(const std::string& str){
    for(char c:str){
        if(!std::isalpha(c) && !std::isspace(c)){
            return false;
        }
    }
    return true;
}