/*
 * FileName:     code_fix
 * CreatedDate:  2020-05-31 02:35:13 +0900
 * LastModified: 2020-05-31 02:53:31 +0900
 */

#include <stdio.h>
#include <stdlib.h>
int dp[101][10001];
int main(void){
    int n;scanf("%d",&n);
    int sum=0;
    int *w = malloc(n*sizeof(int));
    for(int i=0;i<n;i++){
        scanf("%d",w+i);
        sum+=w[i];
    }
    if(sum%2==1){
        printf("impossible\n");
        free(w);
        return 0;
    }
//    int dp[n][sum+1];
    dp[0][0]=1;
    for(int i=0;i<n-1;i++){
        for(int j=0;j<sum+1;j++){
            if(dp[i][j]==1){
                dp[i+1][j+w[i]]=1;
                dp[i+1][j]=1;
            }
        }
    }
    if(dp[n-1][sum/2]==1){
        printf("possible\n");
    }
    else{
        printf("impossible\n");
    }
    free(w);
    return 0;
}