#include <iostream>
#include<fstream>
using namespace std;
 
int main() {
	string str;
	while(getline(cin,str))
	{
		int a=0,b=0,count=0;
		if(str[0]=='_'||(str[0]>='0'&&str[0]<='Z')||str[str.size()-1]=='_')
		{
			count++;
			cout<<"Error!"<<endl;
		}
		for(int i=0;i<str.size()&&count==0;i++)
		{
			if(str[i]=='_')
			{
				a++;
				i++;
				if(str[i]=='_')
				{
					count++;
					cout<<"Error!"<<endl;
					break;
				}
				else i--;
			}
			else if(str[i]>'A'&&str[i]<='Z')
			{
				b++;
			}
			else if(str[i]>='0'&&str[i]<='9')
			{
				cout<<"Error!"<<endl;
				count++;
				break;
			}
			else if(str[i]<=47||(str[i]>=91&&str[i]<=96)||str[i]>=123)
			{
				cout<<"Error!"<<endl;
				count++;
				break;
			}
		}
		if(a>=0&&b==0&&count==0)
		{
			for(int i=0;i<str.size();i++)
			{
				if(str[i]=='_')
				{
					i++;
					str[i]-=32;
					cout<<str[i];
				}
				else
				cout<<str[i];
			}cout<<endl;
		}
		else if(a==0&&b>0&&count==0)
		{
			for(int i=0;i<str.size();i++)
			{
				if(str[i]>='A'&&str[i]<='Z')
				{
					cout<<"_";
					str[i]+=32;
					cout<<str[i];
				}
				else
				{
					cout<<str[i];
				}
			}cout<<endl;
		}
		else if(a>0&&b>0)
		cout<<"Error!"<<endl;
	//}
	}
	// your code here
 
	return 0;
}

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