#include <iostream>
#include <string>
#include <sstream>
 
using namespace std;
 
   int main()
     {
std::string line;
 
    char c;
    while (std::getline(std::cin, line))
    {
        std::stringstream ss(line);
		ss >> c;
        if (! ( ( c >= 'a' && c <= 'z' ) || ( c >= 'A' && c <= 'Z' ) ) ) {
 
     // if it's not within bounds, then it's not a character
 
     std::cout << "Error!" << std::endl;
 
     // you can probably just return here as soon as you find a non-letter char,
     // but it's up to you to decide how you want to handle it exactly
	}
		else {
				std::cout << "its characters!" << std::endl;
				break;
		}
 
       // std::cout << "Error! Insert only positive integers." << std::endl;
    }
       return 0; 
    }

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