// yukicoder: No.4 おもりと天秤
// 2019.4.7 bal4u
// dp

#include <stdio.h>

int w[102]; int N;
char dp[10205];

int check(int goal)
{
	int i, j;

	dp[0] = 1;
	for (i = 0; i < N; i++) {
		for (j = 0; j < goal; j++) if (dp[j]) dp[j + w[i]] = 1;
	}
	return dp[goal] == 1;
}

int main()
{
	int i, goal;
	char *msg[] = { "impossible", "possible" };

	scanf("%d", &N);
	goal = 0; for (i = 0; i < N; i++) scanf("%d", w + i), goal += w[i];
	if (goal & 1) puts(msg[0]);
	else puts(msg[check(goal >> 1)]);
	return 0;
}