#include <iostream>
#include <sstream>
#include <math.h>
#include <vector>
#include <array>
#include <algorithm>
#include <queue>
#include <numeric>
#include <map>
#include <set>
#include <bitset>

using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define SUM(a) accumulate(ALL(a), 0)
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

typedef pair<int, int> pos;
int pos::*x = &pos::first;
int pos::*y = &pos::second;

int dxy[] = {0, 1, 0, -1, 0};

/*================================*/

int N;
vector<int> W;
int target;

map<string, bool> cache;

bool ok(int i, int sum) {
    stringstream ss;
    ss << i << "-" << sum;
    string key = ss.str();
    if (cache[key]) return cache[key];
    if (sum == target) return true;
    if (i >= N) return false;
    return cache[key] = (ok(i+1, sum) || ok(i+1, sum+W[i]));
}

signed main()
{
    cin >> N;
    W.resize(N);
    REP(i,N) cin >> W[i];

    int total = SUM(W);
    if (total % 2 == 1) {
        cout << "impossible" << endl;
        return 0;
    }
    target = total / 2;
    cout << (ok(0, 0) ? "possible" : "impossible") << endl;

    return 0;
}