POJ 2470

 #include<iostream>
 #include<stdio.h>
 #include<vector>
 using namespace std;

 int main()
 {
     //freopen("acm.acm","r",stdin);
     vector<int> coll;
     int num;
     int a;
     int i;
     bool * boo;
     while()
     {
     scanf("%d",&num);
     if(num == )
         break;
     boo = new bool[num];
     memset(boo,false,sizeof(bool)*num);
     for(i = ; i < num; ++ i)
     {
         scanf("%d",&a);
         coll.push_back(a);
     }
     for(i = ; i < num; ++ i)
     {
         if(boo[i])
         {
             continue;
         }
         else
         {
         if(coll[coll[i] - ] != i +)
         {
             cout<<"not ambiguous"<<endl;
             break;
         }
         else
         {
             boo[coll[i] - ] = true;
             //boo[i] = true;
         }

         }

     }
     if(i == num)
     {
         cout<<"ambiguous"<<endl;
     }
     delete[] boo;
     coll.clear();
     }
 }