#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];
bool dp[101][20001];

int main() {
	cin >> n;
	REP(i, n) scanf("%d", w + i);
	
	dp[0][10000] = true;
	
	REP(i, n) REP(j, 20001) {
		if (!dp[i][j]) continue;
		
		if (j + w[i] <= 20000) dp[i + 1][j + w[i]] = true;
		if (j - w[i] >= 0) dp[i + 1][j - w[i]] = true;
	}
	
	puts(dp[n][10000] ? "possible" : "impossible");
	
	return 0;	
}