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

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

int main(void){
    
    int in[102];
    int N;
    int N_T;
    int sum = 0;
    int half_sum = 0;
    
    scanf("%d", &N);
    
    N_T = N;
    
    while(N--){
        scanf("%d", &in[N]);
        sum += in[N];
    }
    
    if(sum%2 != 0){
        printf("impossible\n");
        return 0;
    }
    
    half_sum = sum/2;
    sum = 0;
    
    qsort((void *)in, N_T, sizeof(int), asc_sort);
    
    for(int i=0; i<N_T; i++){
        sum += in[i];
        if(sum == half_sum){
            printf("possible\n");
            break;
        }
    }
    
    return 0;
}