#include <stdlib.h>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#define rep(i,n)	for(int i=0;i<n;i++)
#define srep(i,a,n)	for(int i=a;i<n;i++)
#define REP(i,n)	for(int i=0;i<=n;i++)
#define SREP(i,a,n)	for(int i=a;i<=n;i++)
#define rrep(i,n)	for(int i=n-1;i>=0;i--)
#define RREP(i,n)	for(int i=n;i>=0;i--)
#define scan(x) cin >> x
#define print(x) cout << x << endl
#define fastcin {\
    cin.tie(0);\
    ios::sync_with_stdio(false);\
}
using namespace std;
typedef long long ll;
/* Coding Space */
int N;
int W[101];
int sum, half;
string ans = "impossible";
bool dp[101][5001];
int main(void) {
	fastcin;
	scan(N);
	SREP(n, 1, N) {
		scan(W[n]);
		sum += W[n];
	}
	dp[0][0] = true;
	half = sum / 2;
	SREP(n, 1, N) {
		RREP(w, half) {
			dp[n][w] = dp[n - 1][w];
			if (w + W[n] <= half) dp[n][w + W[n]] |= dp[n][w];
		}
	}
	if (dp[N][half]) ans = "possible";
	if (sum % 2) ans = "impossible";
	print(ans);
	return 0;
}