#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <math.h>
#include <vector>
#include <queue>
#include <algorithm>
#include <sstream>
#include <string>
#include <map>

using namespace std;

#define FOR(I,N) for(int I = 0; I < (int)(N); I++)
#define FIN(V) cout<<V<<endl
#define pb push_back
#define INF (1 << 30)

typedef pair<int, int> P;

string sValueOf(int v){stringstream ss;ss<<v;return ss.str();}
int parseInt(string v){int i;stringstream ss(v);ss>>i;return i;}
void fast_io() {cin.tie(0); ios::sync_with_stdio(false);}

int n;
int w[101];
bool ans = false;
bool memo[101][10001] = {{0}};

void saiki(int at,int x){
	if(ans)return;
	if(memo[at][x])return;
	memo[at][x] = true;
	if(at==n){
		int y = 0;
		int s = 0;
		FOR(i,at){
			s+=w[i];
		}
		y = s-x;
		///cout<<x<<" "<<y<<endl;
		if(x==y)ans = true;
		return;
	}
	saiki(at+1,x);
	saiki(at+1,x+w[at]);
	return;
}

int main(){
	int i,j;
	cin>>n;
	FOR(i,n)cin>>w[i];
	saiki(0,0);
	cout<<(ans?"possible":"impossible")<<endl;
	return 0;
}