#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
int main()
{
    int n,w[100],i,j,sum = 0;
    bool table[101][10001] = {false};

    scanf("%d",&n);
    for (i = 0; i < n; i++)
    {
        scanf("%d",&w[i]);
        sum += w[i];
    }
    if(sum % 2 == 0)
    {
        sum /= 2;
        if(sum < w[n - 1])
        {
            printf("impossible\n");
        }
        else
        {
            table[0][0] = true;
            for (i = 0; i < n; i++)
            {
                for (j = 0; j <= sum; j++)
                {
                    table[i + 1][j] |= table[i][j];
                    if(j >= w[i])table[i + 1][j] |= table[i][j - w[i]];
                }
            }
            if(table[n][sum])printf("possible\n");
            else printf("impossible\n");
        }
    }
    else
    {
        printf("impossible\n");
    }
    

}