/*  This Code is Submitted by wywcgs for Problem 2045 on 2005-10-02 at 13:34:20 */ 
#include <stdio.h>
#define  MAX  100000

int main()
{
	long n, i, a[MAX+1];
	int flag;
	
	while(scanf("%ld", &n) == 1) {
		if(n == 0) {
			return 0;
		} else {
			for(i = 1; i <= n; i++) {
				scanf("%ld", &a[i]);
			}
			flag = 1;
			for(i = 1; i <= n; i++) {
				if(a[a[i]] != i) {
					flag = 0;
					break;
				}
			}
			if(flag == 1) {
				printf("ambiguous\n");
			} else {
				printf("not ambiguous\n");
			}
		}
	}
	
	return 0;
}