#include <iostream>
#include <string>
#include <boost/algorithm/string.hpp>
#include <iostream>
#include <bits/stdc++.h>
using namespace std;
int main() {
// way 1
string s1 = "HeNrY DeUtScH";
boost::to_lower(s1);
cout << s1 << endl;
// way 2
string s2 = "HeNrY DeUtScH";
transform(s2.begin(), s2.end(), s2.begin(), ::tolower); //lowercase
cout << s2 << endl;
// way 3
string s3 = "HeNrY DeUtScH";
for (int i = 0; i < s3.size(); i++) cout << (char) tolower(s3[i]);
cout << endl;
return 0;
}