#include<iostream>
using namespace std;
#define rep(i,n) for(int i = 0; i < n; i++)
#define MAX_W 100*101
	
int main(){
	int N, W, sum = 0;
	bool flag[MAX_W] = {true,};
	cin>>N;
	
	rep(i, N){
		cin>>W;
		sum += W;
		for(int j = 100*i; j >= 0; j--)
			if(flag[j] == true) flag[j+W] = true;
	}
	cout<<(sum%2==0&&flag[sum/2]==true?"possible":"impossible")<<endl;
	return 0;
}