#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <functional>
#include <tuple>
#include <climits>
#include <algorithm>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <set>

using namespace std;

std::vector<int> weights;

std::vector<std::vector<int>> dp;
bool solve(int index, int left, int right)
{
    if(dp[index][left] != -1)
        return dp[index][left]==1;
    if(index == weights.size()) {
        if(left == right) return true;
        return false;
    }
    dp[index][left] = (solve(index+1, left+weights[index], right) || solve(index+1, left, right+weights[index]))?1:0;
    return dp[index][left]==1;
}

int main()
{
    int N;
    cin >> N;
    weights.resize(N);
    for(auto &weight : weights) cin >> weight;
    dp.resize(N+1);
    for(int i=0; i<N+1; i++)
        dp[i].resize(100*100, -1);
    cout << (solve(0, 0, 0)?"possible":"impossible") << endl;
}