#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));


int main(int argc, char const *argv[])
{
  vector<vector<int>> dp(101,vector<int>(1001,0));
  int N; cin >> N;
  vector<int> W(N);
  for(auto &e :W)cin >> e;
  dp[0][0] = 1;
  for(int i=0;i<N;++i)
  {
    for(int j=0;j<=1000;++j)
    {
      if(dp[i][j])
      {
        if(j+W[i] <= 1000)dp[i+1][j+W[i]] = 1;
        if(j - W[i] >= 0)dp[i+1][j-W[i]] = 1;
      }
    }
  }
  if(dp[N][0])std::cout << "possible" << std::endl;
  else std::cout << "impossible" << std::endl;
}