#include <iostream>
#include <vector>
int main(){
	int N;std::cin>>N;
	std::vector<int> W(N);for(auto& w:W)std::cin>>w;
	int sum=0;
	for(auto& w:W)sum+=w;
	std::vector<bool> X(2*sum+1);
	X[0]=1;
	for(auto& w:W)for(int i=2*w;i<=2*sum;i++)X[i]=X[i-2*w]|X[i];
	std::cout<<(X[sum]?"possible":"impossible");
}