#include <iostream>
using namespace std;
string extract_special_characters(string s) {
int len = s.length();
string pecial_characters = "";
for (int i = 0; i < len; i++) {
char ch = s.at(i);
if (!isalnum(ch) || ch == ' ')
pecial_characters += ch;
}
return pecial_characters;
}
int main()
{
string s("c++14$vb.net&^java*() php <>/python 3.7.3");
cout << extract_special_characters(s);
return 0;
}
/*
run:
++$.&^*() <>/ ..
*/