#include<iostream>
using namespace std;
void main()
{
	char ch,temp,last;
	bool statment=true,final=true;
	cin.get(ch);
	temp = ch;
	cin.get(ch);
	if(ch >= 65 && ch<=90)
		final = false;
	while(statment)
	{
		temp = ch;
		cin.get(ch);
		if(ch=='\n')
		{
			statment = false;
			last = temp;
		}
	}
	for(int x =0;x<3;x++)
	{
		cin.get(ch);
		temp = ch;
		cin.get(ch);
		statment = true;
		if(ch >= 65 && ch<=90)
		final = false;
		while(statment)
		{
			temp = ch;
			cin.get(ch);
			if(ch=='\n')
			{
				if(temp!=last)
					final = false;
				statment = false;
			}
		}
	}
	if(final)
		cout << "Valid" << endl;
	else cout << "Not valid" << endl;
}