#include <stdio.h>
#include <stdlib.h>

int compare_int(const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
}

int main()
{
    int n,w[100],i,j,sum = 0,sumw[101] = {0};

    scanf("%d",&n);
    for (i = 0; i < n; i++)
    {
        scanf("%d",&w[i]);
        sum += w[i];
    }

    if(sum % 2 == 0)
    {
        sum /= 2;
        qsort(w,n,sizeof(int),compare_int);
        for (i = 0; i < n; i++)
        {
            sumw[i + 1] = w[i] + sumw[i];
        }
        
        if(sum < w[0])
        {
            printf("impossible\n");
        }
        else
        {
            for (i = n; i > 0; i--)
            {
                if(sum > sumw[i])
                {
                    sum -= w[i + 1];
                    if(sum == 0)break;
                }
            }
            if(i == 0)printf("impossible\n");
            else printf("possible\n");
        }
    }
    else
    {
        printf("impossible\n");
    }
    

}