#include <iostream>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <cstdio>
#include <sstream>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <set>
#include <map>
#include <list>
#include <iomanip>

#define INF 1000000001
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (a); i >= (b); i--)

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
const double PI = acos(-1.0);

int N;
int W[101];

int dp[10001][101];

int main()
{
	ios::sync_with_stdio(false);

	cin >> N;
	FOR(i,0,N) cin >> W[i];

	memset(dp, 0, sizeof(dp));
	int s=0;
	FOR(i,0,N) s+=W[i];
	if (s%2) {
		cout << "impossible\n";
	} else {
		s/=2;
		FOR(i,0,N+1) dp[0][i] = 1;
		FOR(i,1,s+1) FOR(j,1,N+1) {
			dp[i][j] = dp[i][j-1];
			if (i-W[i-1]>=0) dp[i][j] |= dp[i-W[i-1]][j-1];
		}
		if (dp[s][N]) cout << "possible\n";
		else cout << "impossible\n";
	}
	
	return 0;
}