// Standard I/O
#include <iostream>
#include <sstream>
#include <cstdio>
// Standard Library
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <cmath>
// Template Class
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
// Container Control
#include <algorithm>

using namespace std;

#define rep( i, n ) for( int i = 0; i < n; ++i )
#define irep( i, n ) for( int i = n-1; i >= 0; --i )
#define reep( i, s, n ) for ( int i = s; i < n; ++i )
#define ireep( i, n, s ) for ( int i = n-1; i >= s; --i )
#define foreach(itr, x) for( typeof(x.begin()) itr = x.begin(); itr != x.end(); ++itr)

#define mp( a, b ) make_pair( a, b )
#define pb( a ) push_back( a )
#define all( v ) v.begin(), v.end()
#define fs first
#define sc second
#define vc vector

// for visualizer.html
double SCALE = 1.0;
double OFFSET_X = 0.0;
double OFFSET_Y = 0.0;
#define LINE(x,y,a,b) cerr << "line(" << SCALE*(x) + OFFSET_X << ","	\
	<< SCALE*(y) + OFFSET_Y << ","										\
	<< SCALE*(a) + OFFSET_X << ","										\
	<< SCALE*(b) + OFFSET_Y << ")" << endl;
#define CIRCLE(x,y,r) cerr << "circle(" << SCALE*(x) + OFFSET_X << ","	\
	<< SCALE*(y) + OFFSET_Y << ","										\
	<< SCALE*(r) << ")" << endl;

typedef long long ll;
typedef complex<double> Point;

typedef pair<int, int> pii;
typedef pair<int, pii> ipii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector< vector<int> > vii;
typedef vector< vector<double> > vdd;

typedef vector<int>::iterator vi_itr;

const int IINF = 1 << 28;
const double INF = 1e30;
const double EPS = 1e-10;
const double PI = acos(-1.0);

// Direction : L U R D
const int dx[] = { -1, 0, 1, 0};
const int dy[] = { 0, -1, 0, 1 };

int dp[105][10010] = { 0 };
int main()
{
	int N, sum = 0;
	int W[100];

	cin >> N;
	rep(i, N) {
		cin >> W[i];
		sum += W[i];
	}

	dp[0][W[0]] = 1;
	rep(i, N-1){
		rep(j, 10010){
			if( dp[i][j] != 0 ){
				dp[i+1][j+W[i+1]] = 1;
			}
		}
	}

	bool ans = false;
	rep(i, N){
		rep(j, 10010){
			if( dp[i][j] != 0 && j + j == sum ){
				ans = true;
				break;
			}
		}
		if( ans ) break;
	}
	cout << (ans ? "possible" : "impossible") << endl;
}