#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)




int N;
int W[100];
//-----------------------------------------------------------------
bool dp[101][10101];
int main() {
	cin >> N;
	rep(i, 0, N) cin >> W[i];

	dp[0][0] = true;
	rep(i, 0, N) rep(j, 0, 10101) if(dp[i][j]){
		dp[i + 1][j] = true;
		int jj = j + W[i];
		if (jj <= 10000) dp[i + 1][jj] = true;
	}

	string ans = "impossible";
	int sm = 0;
	rep(i, 0, N) sm += W[i];
	rep(j, 0, sm) {
		int oth = sm - j;
		if (dp[N][j] && j == oth) ans = "possible";
	}
	cout << ans << endl;
}