#include <bits/stdc++.h>
using namespace std;
int main()
{
	string a;
	cin >> a;
	int n = a.size();
	for (int i = 0; i < n; i++)
    {
		if (i == 0)
            cout << (char)(a[i] + 32);
		else if (a[i] >= 'A' && a[i] <= 'Z')
            cout << "_" << (char)(a[i] + 32);
		else
            cout << a[i];
	}
    return 0;
} //已AC