#include <bits/stdc++.h>
using namespace std;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FORR(x,arr) for(auto&& x:arr)
#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define RFOR(i,a,b) for (int i = (b)-1; i >= (a); i--)
#define REP(i,n) for (int i = 0; i < (n); i++)
#define RREP(i,n) for (int i = (n)-1; i >= 0; i--)
#define ALL(x) (x).begin(), (x).end()
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define RITR(x,c) for(__typeof(c.rbegin()) x=c.rbegin();x!=c.rend();x++)
#define BIT(n) (1LL<<(n))
#define SZ(x) ((int)(x).size())
typedef long long ll;
// -------------------------------------

int N;
int W[100];
bool dp[100*100+1];

int main() {
  cin >> N;
  REP(i, N) cin >> W[i];
  
  int S = accumulate(W, W+N, 0);
  if (S%2) {
    puts("impossible");
    return 0;
  }

  dp[0] = true;
  REP(i, N) RREP(j, S/2) if (dp[j]) dp[j+W[i]] = true;

  puts(dp[S/2] ? "possible" : "impossible");

  return 0;
}