#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long mod = 1000000007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;


int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/
	ll N; scanf("%lld", &N);
	vector<ll> w(N);
	ll sum = 0;
	for (ll i = 0; i < N; i++) {
		scanf("%lld", &w[i]);
		sum += w[i];
	}
	if (sum & 1) {
		puts("impossible");
		return 0;
	}
	vector<vector<bool>> dp(N + 1, vector<bool>(sum + 1, false));
	dp[0][0] = true;
	for (ll i = 0; i < N; i++) {
		for (ll j = 0; j <= sum; j++) {
			if (!dp[i][j]) continue;
			dp[i + 1][j + w[i]] = true;
			dp[i + 1][j] = true;
		}
	}
	if (dp[N][sum / 2]) puts("possible");
	else puts("impossible");
	return 0;
}