#include "bits/stdc++.h"
#define REP(i,n,N) for(int i=(n); i<(N); i++)
#define RREP(i,n,N) for(int i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const int inf=1e9+7;

int N;
int W[110];
bool dp[110][10010];
int sumw;
int main() {
    cin>>N;
    REP(i,0,N) {
        cin>>W[i];
        sumw+=W[i];
    }
    if(sumw%2){
        p("impossible");
        return 0;
    }
    dp[0][0]=true;
    REP(i,0,N){
        REP(j,0,sumw/2+1){
            dp[i+1][j] |= dp[i][j];
            dp[i+1][j+W[i]] |= dp[i][j];
        }
    }
    p(dp[N][sumw/2]?"possible":"impossible");
    return 0;
}