#include <iostream>
#include <vector>
#include <fstream>
#include <cstdio>

using namespace std;

int main()
{
	int n;
	FILE *in = fopen("ambiguous.in", "r");
	while(1) {
		fscanf(in, "%d", &n);
		if (n == 0) return 0;
		vector<int> V, V2;
		V.assign(n, -1);
		V2.assign(n, -1);
		for(int i = 0; i < n; ++i) {
			int a;
			fscanf(in, "%d", &a);
			a--;
			V[i] = a;
			V2[a] = i;
		}
		bool ambig = true;;
		for(int i = 0; i < n; ++i) {
			if (V[i] != V2[i]) {
				ambig = false;
				break;
			}
		}
		if (ambig) cout << "ambiguous" << endl;
		else cout << "not ambiguous" << endl;
	}
	return 0;
}