#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

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

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int n;
int w[100];
int dp[101][501][501];

bool dfs(int pos, int a, int b) {
	if (pos == n) return a == b;
	if (~dp[pos][a][b]) return dp[pos][a][b];
	
	int res = 0;
	if (a + w[pos] <= 500 && dfs(pos + 1, a + w[pos], b)) res = 1;
	if (b + w[pos] <= 500 && dfs(pos + 1, a, b + w[pos])) res = 1;
	
	return dp[pos][a][b] = res;
}

int main() {
	cin >> n;
	REP(i, n) scanf("%d", w + i);
	
	memset(dp, -1, sizeof(dp));
	
	puts(dfs(0, 0, 0) ? "possible" : "impossible");
	
	return 0;	
}