#include <bits/stdc++.h>

using namespace std;
const int MAXW = 10005;
const int MAXN = 100;

bool dp[MAXN][MAXW];
int W[MAXN];

int main() {
  int N;
  scanf("%d", &N);
  int total = 0;
  for (int i = 0; i < N; ++i) {
    scanf("%d", &W[i]);
    total += W[i];
  }

  if (total & 1) {
    puts("impossible");
    return 0;
  }
  memset(dp, 0, sizeof(dp));
  dp[0][0] = true;
  for (int i = 0; i < N; ++i) {
    for (int j = 0; j < MAXW; ++j) {
      if (dp[i][j]) {
	dp[i + 1][j + W[i]] = true;
	dp[i + 1][j] = true;
      }
    }
  }
  if (dp[N][total / 2]) puts("possible");
  else puts("impossible");
  return 0;
}