#include <iostream>
#include <numeric>

#define rep(i, a) FOR(i, 0, a)
#define FOR(i, a, b) for(int i = a; i < b; ++i)

int n;
int w[101];
int dp[105][10005];

int main(){
	std::cin >> n;
	rep(i, n)std::cin >> w[i];
	dp[0][0] = 1;
	rep(i, n)rep(j, 10001){
		if (dp[i][j] != 0){
			dp[i + 1][j] = 1;
			if (j + w[i] < 10001)dp[i + 1][j + w[i]] = 1;
		}
	}
	if (std::accumulate(w, w + n, 0) % 2 != 0)std::cout << "impossible" << std::endl;
	else if (dp[n][std::accumulate(w, w + n, 0) / 2])std::cout << "possible" << std::endl;
	else std::cout << "impossible" << std::endl;
	return 0;
}