#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

int N, sum = 0;
int w[110];

bool dp[10010];
int main()
{
    cin >> N;
    for(int i = 0; i < N; i++)
    {
        cin >> w[i];
        sum += w[i];
    }

    memset(dp, false, sizeof(dp));

    dp[0] = true;

    for(int i = 0; i < N; i++)
    {
        for (int j = 10010 - 1 - w[i]; j >= 0; j--)
		{
			dp[j + w[i]] |= dp[j];
		}
    }

    if (sum % 2 == 1 || !dp[sum / 2]) cout << "impossible" << endl;
	else cout << "possible" << endl;
}