#include <iostream>
using namespace std;
string extract_characters(string s) {
int len = s.length();
string chars = "";
for (int i = 0; i < len; i++) {
char ch = s.at(i);
if (isalpha(ch))
chars += ch;
}
return chars;
}
int main()
{
string s("c++14$vb.NET&^java*() php <>/python 3.7.3");
cout << extract_characters(s);
return 0;
}
/*
run:
cvbNETjavaphppython
*/