#include<iostream>

#define DEBUG
#define NMAX 100
#define WMAX 100
#define DPSIZE (WMAX*WMAX+1)

using namespace std;

int main(){
    int N;
    int W[NMAX];
    int sum;
    int dp[DPSIZE];

    cin>>N;
    for(int i=0;i<N;i++){
        cin>>W[i];
    }

    sum=0;
    for(int i=0;i<N;i++){
        sum+=W[i];
    }

    if(sum%2==1) cout<<"impossible"<<endl;
    else{
        for(int i=0;i<DPSIZE;i++){
            dp[i]=-1;
        }
        dp[0]=0;
        for(int i=0;i<N;i++){
            for(int j=DPSIZE-1;j>=0;j--){
                if(dp[j]!=-1) dp[j+W[i]]=0;
            }
        }
        if(dp[sum/2]==0) cout<<"possible"<<endl;
        else cout<<"impossible"<<endl;
    }
}