#include <stdio.h>

int main(void) {
	int i, j, k;
	int n, w[101];
	int total = 0;
	int memo[10001] = {0};
	int memo2[10001] = {0};
 
	scanf("%d", &n);
	for(i = 0;i < n;i++){
		scanf("%d", &w[i]);
		total += w[i];
	}
	if(total % 2 == 1){
		printf("impossible\n");
		return 0;
	}
	for(j = 0;j < n;j++){
		for(i = 0;i < total;i++){
			if(memo[i] == 1){
				for(k = i + w[j];k <= total;k += w[j]){           
					if(memo[k] == 0){
						memo2[k] = 1;
						break;
					}
				}
			}
		}
		for(i = w[j];i <= total;i += w[j]){           
			if(memo[i] == 0){
				memo2[i] = 1;
				break;
			}
		}
		for(i = 0;i < total;i++){
			memo[i] = memo[i] | memo2[i];
		}
	}

	if(memo[total / 2] == 1){
		printf("possible\n");
	}
	else{
		printf("impossible\n");
	}
	return 0;
}