#include <stdio.h>

int memo[101][5001],done[101][5001];
int N,W[100],s;

int max(int a,int b){
	if(a>b){return a;}else{return b;}
}

int dp(int a,int b){
	if(done[a][b] == 1){return memo[a][b];}

	memo[a][b] = 0;
	if(b+W[a]<=s){
		memo[a][b] = dp(a+1,b+W[a]);
	}
	memo[a][b] = max(memo[a][b],dp(a+1,b));

	done[a][b] = 1;
	return memo[a][b];
}

int main(void){
	int i,j;

	scanf("%d",&N);
	s = 0;
	for(i=0;i<N;i++){
		scanf("%d",&W[i]);
		s = s + W[i];
	}
	if(s%2 == 1){
		printf("impossible\n");
		return 0;
	}
	s = s/2;

	for(i=0;i<N;i++){
		for(j=0;j<s;j++){
			done[i][j] = 0;
		}
	}
	for(i=0;i<=N;i++){
		done[i][s] = 1;
		memo[i][s] = 1;
	}
	for(i=0;i<s;i++){
		done[N][i] = 1;
		memo[N][i] = 0;
	}

	if(dp(0,0) == 1){
		printf("possible\n");
	}else{
		printf("impossible\n");
	}

}