#include<bits/stdc++.h>
using namespace std;
int main()
{
	char x,z;
	long long w,y;
	cin>>x>>y>>z>>w;
	if(x==z && x>='a' && x<='z')
	{
		cout<<"valid"<<endl;
		if(y<=w) 
		{
			cout<<w-y+1<<endl;	
		}
		else
		{
			cout<<y-w+1<<endl;	
		}	
	}
	else
	{
		cout<<"Iivalid"<<endl;
		cout<<-1<<endl;
	}
	return 0;
}