#include<iostream>
using namespace std;
int main()
{
	int n , *num ;
	while(cin >> n && n )
	{
		num = new int[n+1] ;
		int i , j ;
		for( i = 1 ; i <= n ; i++ )
		{
			scanf("%d",&num[i]);
		}
		for( j = 1 ; j <= n ; j++ )
		{
			if( num[num[j]] != j )
			{
				break ;
			}
		}
		if( j == n + 1 )
		{
			cout << "ambiguous" <<endl;
		}
		else
		{
			cout << "not ambiguous" << endl;
		}
	}
	return 0 ;
}