#include <stdio.h>
#include <stdlib.h>

int main(){
    
    int n,i,bad;
    int pos1[100470];
    int pos2[100470];
    
    scanf("%d\n",&n);
    
    while (n){
          
          for (i=1;i<n+1;i++){pos2[i]=0;}
          
          for (i=1;i<n+1;i++){scanf("%d ",&pos1[i]);
          pos2[pos1[i]]=i;
          }
          
          bad=0;
          for (i=1;i<n+1;i++){
              if (pos1[i]!=pos2[i]){bad=1;}
              }
          
          if (bad){printf("not ambiguous\n");}
          else {printf("ambiguous\n");}
          
          scanf("%d\n",&n);
          }

// system("pause");    
    
 return 0;   
}