#include<stdio.h>
int N;
int W[100];
int dp[101][10001];
int search(int i,int w);
main(){
    scanf("%d",&N);
    int sum = 0;
    for(int i = 0;i < N;i++){
        scanf("%d",&W[i]);
        sum += W[i];
    }
    dp[0][0] = 1;
    for(int i = 1;i <= N;i++){
        for(int j = 0;j < sum+1;j++){
            if(dp[i-1][j]){
                dp[i][j]++;
                dp[i][j+W[i-1]]++;
            }
        }
    }
    printf("%s\n",sum%2?"impossible":dp[N][sum/2]?"possible":"impossible");
}