#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
using namespace std;

#define FOR(i,s,e) for(int i = (s);i <= (e);i++)

vector<vector<bool>> dp(101,vector<bool>(10100,false));

int W[101];

int N;
int total = 0;

int main()
{
    cin >> N;
    FOR(i,0,N - 1)
    {
        cin >> W[i];
        total += W[i];
    }
    if(total % 2 == 1)
    {
        cout << "impossible" << endl;
        return 0;
    }

    dp[0][0] = true;

    FOR(i,0,N - 1)
    {
        FOR(j,0,5049)
        {
            dp[i + 1][j] = dp[i][j] || dp[i + 1][j];
            if(dp[i][j] && j + W[i] <= 10000)
            {
                dp[i + 1][j + W[i]] = true;
            }
        }
    }

    if(dp[N][total / 2]) cout << "possible" << endl;
    else cout << "impossible" << endl;
    return 0;
}