#include <iostream>
#include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <algorithm>
#include <functional>
#include <limits.h>
#include <bitset>

#include <tuple>
#include <unordered_map>

#define mp make_pair
#define mt make_tuple
#define pb push_back
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;

const int INF = 1 << 29;
const double EPS = 1e-9;

const int dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
int N;
int dp[110][2500];
vector<int> weight;
int memo(int pos, int sum) {
  if (pos == N) {
    if (sum == 1250) {
      return 1;
    } else {
      return 0;
    }
  }
  if (dp[pos][sum] >= 0) {
    return dp[pos][sum];
  }
  int res = 0;
  res |= memo(pos + 1, sum + weight[pos]);
  res |= memo(pos + 1, sum - weight[pos]);
  return dp[pos][sum] = res;
}

int main() {
  int pos = 1250;
  memset(dp, -1, sizeof(dp));
  cin >> N;
  for (int i = 0; i < N; i++) {
    int x;
    cin >> x;
    weight.push_back(x);
  }
  if (memo(0, pos) == 1) {
    cout << "possible" << endl;
  } else {
    cout << "impossible" << endl;
  }
  return 0;
}