#include <stdio.h>

int f[110][100010] = {};
const int inf = -1000000;

int max(int a, int b) {
	return a > b ? a : b;
}

int main() {
	int n;
	int arr[110];
	int i, j;
	int sum = 0;

	scanf("%d", &n);

	for (i = 1; i <= n; i++) {
		scanf("%d", &arr[i]);
		sum += arr[i];
	}

	if (sum % 2 != 0) {
		printf("impossible");
	}
	else {
		sum /= 2;

		for (i = 1; i <= n; i++) {
			for (j = 0; j <= sum; j++) {
				f[i][j] = inf;
			}
		}

		f[1][arr[1]] = 1;

		for (i = 2; i <= n; i++) {
			for (j = 0; j <= sum; j++) {

				if (j - arr[i] >= 0) {
					f[i][j] = max(f[i - 1][j], f[i - 1][j - arr[i]] + 1);
				}
			}
		}

		if (f[n][sum] >= 0) {
			printf("possible");
		}
		else {
			printf("impossible");
		}

		getchar(); getchar();
		return 0;
	}
}