#include <stdio.h>

int N;
int W[100];

int main() {
    scanf("%d", &N);
    
    for (int i=0; i<N; i++) {
        scanf("%d", &(W[i]));
    }
    
    int sum = 0;
    for (int i=0; i<N; i++) {
        sum += W[i];
    }
    
    if ((sum % 2) == 1) {
        printf("impossible\n");
        return 0;
    }
    
    // bubble sort
    int flag = 0;
    while (1) {
        flag = 0;
        for (int i=0; i<N-1; i++) {
            if (W[i] < W[i+1]) {
                int tmp = W[i];
                W[i] = W[i+1];
                W[i+1] = tmp;
                flag = 1;
            }
        }
        if (flag == 0)
            break;
    }

    if (isPossible(sum/2-W[0], 1))
        printf("possible\n");
    else
        printf("impossible\n");
}

int isPossible(int target, int pos) {

    if (target == 0)
        return 1;
    if (pos == N)
        return 0;

    if (target < W[pos])
        return isPossible(target, pos+1);

    if (isPossible(target-W[pos], pos+1) > 0)
        return 1;
    if (isPossible(target, pos+1) > 0)
        return 1;

    return 0;
}