#include <iostream>
#include <cstring>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))
#define RREP(i, n)          for(int(i)=(n)-1;(i)>=0;--(i))

const int MAXN = 100, MAXW = 100;
const int MAXSUMW = MAXN * MAXW / 2;

int main(){
    int N, W;
    cin >> N;
    if(N < 2 || N > MAXN){ cerr << N << endl; };

    int sum = 0;
    bool dp[MAXSUMW+1];
    memset(dp,0,sizeof(dp));
    dp[0] = true;

    REP(i,N){
        cin >> W;
        if(W < 1 || W > MAXW){ cerr << W << endl; };
        RREP(i,min(sum,MAXSUMW)+1){
            if(!dp[i]) continue;
            if(i+W > MAXSUMW) continue;
            dp[i+W] = true;
        }
        sum += W;
    }
    if(sum % 2 || !dp[sum/2]){
        cout << "impossible" << endl;
    } else {
        cout << "possible" << endl;
    }
    return 0;
}