#include <iostream>
#include <utility>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <functional>
#include <iomanip>
#include <map>
#include <set>
#include <queue>
using namespace std;
using ll = long long int;
#define chmax(x,y)  (x) = ((x) > (y)) ? (x) : ((x) = (y));
#define chmin(x,y)  (x) = ((x) < (y)) ? (x) : ((x) = (y));
const int INF = 1e9;
const ll INFL = 1e18;
const int Mod = 1e9 + 7;
const int dx[] = {0,1,0,-1};
const int dy[] = {1,0,-1,0};


int main(int argc, char const *argv[])
{
  int N; cin >> N;
  vector<int> W(N); for(auto &a: W)cin >> a;
  vector<vector<int>> dp(N+1,vector<int>(2001));
  dp[0][0] = 1;
  for(int i=0;i<N;++i)
  {
    for(int j=0;j<1000;++j)
    {
      if(dp[i][j])
      {
        dp[i+1][j+W[i]] = 1;
        int x = abs(j - W[i]);
        dp[i+1][x] = 1;
      }
    }
  }
  if(dp[N][0])std::cout << "possible" << std::endl;
  else std::cout << "impossible" << std::endl;
}