#include<iostream>
using namespace std;
int main()
{
int n=0,i=0;
int a[100001]={0},b[100001]={0};
cin>>n;
while(n!=0)
{
a[0]=0;
for(i=1;i<=n;i++)
{
cin>>a[i];
b[a[i]]=i;
}
for(i=0;i<=n;i++)
{
if(a[i]!=b[i])
{
cout<<"not ambiguous\n";
a[0]=1;
break;
}
}
if(a[0]==0)
{
cout<<"ambiguous\n";
}
cin>>n;
}
return 0;
}
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