#include<bits/stdc++.h>
using namespace std;  
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
#define rep(i,n) for(ll i=0;i<(n);i++)  
#define pii pair<int,int>
#define piii pair<int,pii>
#define mp make_pair
#define pb push_back  
#define ALL(a) (a).begin(),(a).end()
#define FST first
#define SEC second  
const int INF = (INT_MAX/2);
const ll LLINF = (LLONG_MAX/2);
const double eps = 1e-5;
const double PI = M_PI;  
#define DEB cout<<"!"<<endl
#define SHOW(a,b) cout<<(a)<<" "<<(b)<<endl
#define SHOWARRAY(ar,i,j) REP(a,i)REP(b,j)cout<<ar[a][b]<<((b==j-1)?((a==i-1)?("\n\n"):("\n")):(" "))
  
#define DIV 1000000007
typedef vector<ll> Array;
typedef vector<Array> matrix;

int main(){
  int sum = 0,n; cin >> n;
  vi input(n);
  rep(i,n){
    cin >> input[i];
    sum += input[i];
  }
  if(sum % 2){
    cout << "impossible" << endl; return 0;
  }else
    sum /= 2;
  
  int now = 0;
  now = input[0];
  int l = 0,r = 0;
  while(1){
    if(now < sum){
      r++;
      now += input[r];
    }else if(now > sum){
      l++;
      now -= input[l-1];
    }else{
      cout << "possible" << endl;
      return 0;
    }
    if(r == n){
      cout << "impossible" << endl;
      return 0;
    }
  }
}