Uva 10038: Jolly Jumpers

Problem Link:
                 [https://uva.onlinejudge.org/external/100/10038.pdf]
Catagory: Data Structure, Implementation;
Strategy: See Algorithmist
              [http://www.algorithmist.com/index.php/UVa_10038]

Code:

#include<bits/stdc++.h>
#define ll  long long int
using namespace std;


int main()
{
    ll n;
    while(cin>>n)
    {
          ll a[n],v[n];
          set<ll>d;
          for(int i=0; i<n; i++)
            cin>>a[i];
          for(int i=0; i<n-1; i++)
          {ll p=abs(a[i+1]-a[i]);
                if(p>0 && p<n)
            d.insert(p);}

 if(d.size()==n-1)
      cout<<"Jolly"<<endl;
      else
            cout<<"Not jolly"<<endl;
    }}