#include<bits/stdc++.h>
#if 1 && defined(LOCAL)
    #include<LOCAL/LOCAL.hpp>
#else
    #define debug(...)
    #define line
#endif
using namespace std;
typedef long long ll;
typedef long double ld;
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}

int main(){
    int N;
    cin>>N;
    vector<int>a(N);
    for(int i=0;i<N;i++){
        cin>>a[i];
    }
    int sum=accumulate(all(a),0);
    //dp[何番目までの品物を選ぶか{選ばない,0,1,2,3,4,5,....}][作れる重さ]
    vector<vector<bool>>dp(N+1,vector<bool>(sum+1,false));
    dp[0][0] = true;
    for (int i = 0; i < N; ++i) {
        for (int j = 0; j <= sum+1; ++j) {
            dp[i+1][j] = dp[i+1][j]||dp[i][j];
            if (j >= a[i]) dp[i+1][j] = dp[i+1][j]||dp[i][j-a[i]];
        }
    }
    if(sum%2==1){
        cout<<"impossible"<<endl;
    }
    else{
        cout<<(dp[N][sum/2]? "possible":"impossible")<<endl;
    }
}