#include <iostream>
using namespace std;
 
 
 
string strlower(string s) {
	for (int i = 0; i < s.length(); i++) {
		if (s[i] >= 'A' && s[i] <= 'Z')
			s[i] = s[i] + 32;
	}
	return s;
}
 
 
int main() {
	string str, ans = "";
	while (cin >> str && str.length() > 4) {
		for (int i = 0; i < str.length(); ++i)
			if ((str[i] >= 'a' && str[i] <= 'z') || (str[i] >= 'A' && str[i] <= 'Z') || (str[i] >= '0' && str[i] <= '9' ) || (str[i] == ' ')) {
				ans += strlower(str);
			}
	}
	cout << ans;
	return 0;
}

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