#include<bits/stdc++.h>

using namespace std;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    string s;
    cin >> s;
    if(s.front() == '_' || s.back() == '_' || (s.front() >= 'A' && s.front() <= 'Z'))
        cout << "Error!", exit(0);
    bool f1 = 0, f2 = 0;
    for(int i = 0; i < s.size(); i++)
    {
        if(s[i] == '_')
            f1 = 1;
        if(s[i] >= 'A' && s[i] <= 'Z')
            f2 = 1;
    }
    if(f1 & f2)
        cout << "Error!", exit(0);
    string ans = "";
    for(int i = 0; i < s.size(); i++)
    {
        if(s[i] == '_')
        {
            if(s[i + 1] == '_')
                cout << "Error!", exit(0);
            i++;
            ans.push_back(s[i] - 'a' + 'A');
        }
        else if(s[i] >= 'A' && s[i] <= 'Z')
        {
            ans += "_";
            ans.push_back(s[i] - 'A' + 'a');
        }
        else
            ans.push_back(s[i]);
    }
    cout << ans;
}