#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;

static const double EPS = 1e-8;
static const double PI = 4.0 * atan(1.0);
static const double PI2 = 8.0 * atan(1.0);

#define REP(i,n)	for(int i=0;i<(int)n;++i)
#define ALL(c)		(c).begin(),(c).end()
#define CLEAR(v)	memset(v,0,sizeof(v))
#define MP(a,b)		make_pair((a),(b))
#define ABS(a)		((a)>0?(a):-(a))
#define FOR(i,s,n)	for(int i=s;i<(int)n;++i)

#define POSSIBLE "possible"
#define IMPOSSIBLE "impossible"

int N;
int W[100];
int sum;

bool dfs(int s, int i) {
	if (s == sum) return true;
	if (s > sum) return false;
	if (i >= N) return false;
	if (dfs(s + W[i], i + 1)) return true;
	if (dfs(s, i + 1)) return true;
	return false;
}

int main(int argc, char **argv) {
	cin >> N;
	sum = 0;
	REP(i, N) {
		cin >> W[i];
		sum += W[i];
	}
	if (sum % 2 != 0) {
		cout << IMPOSSIBLE << endl;
		return 0;
	}
	sum /= 2;
	sort(W, W + N);
	reverse(W, W + N);
	cout << (dfs(0, 0) ? POSSIBLE : IMPOSSIBLE) << endl;
	return 0;
}