#include <bits/stdc++.h>

using namespace std;

#define INF 100000000
#define YJ 1145141919
#define INF_INT_MAX 2147483647
#define INF_LL 9223372036854775
#define INF_LL_MAX 9223372036854775807
#define EPS 1e-10
#define MOD 1000000007
#define MOD9 998244353
#define Pi acos(-1)
#define LL long long
#define ULL unsigned long long
#define LD long double

#define int long long

using II = pair<int, int>;

int gcd(int a, int b) { return b != 0 ? gcd(b, a % b) : a; }
int lcm(int a, int b) { return a * b / gcd(a, b); }
int extgcd(int a, int b, int &x, int &y) { int g = a; x = 1; y = 0; if (b != 0) g = extgcd(b, a % b, y, x), y -= (a / b) * x; return g; }

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(a)  begin((a)), end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())

const int MAX_N = 105;

int N;
int W[MAX_N];
bitset<2*MAX_N*MAX_N> dp[MAX_N];

signed main()
{
  cin >> N;
  REP(n,N) {
    cin >> W[n];
  }

  dp[0].set(MAX_N*MAX_N);

  REP(n,N) {
    dp[n+1] |= (dp[n] >> W[n]) | (dp[n] << W[n]);
  }

  if(dp[N][MAX_N*MAX_N]) {
    cout << "possible" << endl;
  } else {
    cout << "impossible" << endl;
  }

  return 0;
}