#include<iostream>
#include<algorithm>
#include<math.h>
#include<set>
#include<vector>
#include<map>
#include<functional>
#include<iomanip>
#include<queue>
#include<random>
#include<numeric>
#include<string>
#include<stack>
#include<cstring>
typedef long long ll;
typedef long double ld;
using namespace std;
ll dx[] = { 0,0,1,-1 };
ll dy[] = { 1,-1,0,0 };

ll gcd(ll a, ll b) {
	if (a<b) { return gcd(b, a); }
	else if (a%b) { return gcd(b, a%b); }
	else { return b; }
}
ll lcm(ll a, ll b) {
	return a / gcd(a, b)*b;
}
ll prime(ll x) {
	ll i;
	if (x < 2)return 0;
	else if (x == 2) return 1;
	if (x % 2 == 0) return 0;
	for (i = 3; i*i <= x; i += 2) {
		if (x%i == 0) return 0;
	}
	return 1;
}
int main() {
	ll N;
	cin >> N;
	ll a[1000];
	ll S[1000];
	bool flag = 0;
  	ll sum=0;
	for (ll i = 0; i < N; ++i) {
		cin >> a[i];
      	sum+=a[i];
	}
	S[0] = 0;
	for (ll i = 1; i <= N; ++i) {
		S[i] = S[i - 1] + a[i-1];
	}
	for (ll i = 0; i <= N; i++) {
		if (sum == 2 * S[i])
			flag = 1;
	}
	if (flag)cout << "possible" << endl;
	else cout << "impossible" << endl;

}