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

#define lp(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) lp(i, 0, n)
#define rlp(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); i--)
#define rrep(i, n) rlp(i, 0, n)

#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define all(c) begin(c), end(c)

typedef long long ll;
typedef unsigned long long ull;

const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, -1, 0, 1};

const int MOD = 1e9 + 7;
const int INF = 1 << 28;
const ll INFLL = 1ll << 60;

template<typename T>
inline void unique(T &c){
	sort(all(c));
	c.erase(unique(all(c)), end(c));
}

int n;
int w[110];
bool dp[10010];

int main()
{
	cin >> n;
	rep(i, n) cin >> w[i];

	int s = 0;
	rep(i, n) s += w[i];
	
	if (s & 1){
		cout << "impossible\n";
		return 0;
	}

	dp[0] = true;
	for (int i = 0; i < n; i++){
		for (int j = s; j >= w[i]; j--){
			dp[j] |= dp[j - w[i]];
		}
	}

	cout << (dp[s / 2] ? "possible\n" : "impossible\n");
}