void main() {
	const N = readInt;
	auto W = new int[N];
	foreach (i; 0 .. N) W[i] = readInt;
	int sum = W.sum;
	auto dp = new bool[sum / 2 + 1];
	dp[0] = true;
	foreach (i; 0 .. N) {
		foreach_reverse (j; 0 .. sum / 2 - W[i] + 1) {
			dp[j + W[i]] = dp[j + W[i]] || dp[j];
		}
	}
	bool ok = true;
	ok = ok && sum % 2 == 0;
	ok = ok && dp[sum / 2];
	writeln(ok ? "possible" : "impossible");
}

import std,core.bitop;
string[]_R;
string readString(){while(_R.empty){_R=readln.chomp.split;}auto ret=_R.front;_R.popFront;return ret;}
int readInt(){return readString.to!int;}
long readLong(){return readString.to!long;}
ulong readULong(){return readString.to!ulong;}
real readReal(){return readString.to!real;}
bool chmin(T)(ref T A,T B){if(A>B){A=B;return true;}else{return false;}}
bool chmax(T)(ref T A,T B){if(A<B){A=B;return true;}else{return false;}}
int lowerBound(T)(T[]A,T x){int L=-1,R=cast(int)A.length;while(R-L>1){int mid=(L+R)/2;(A[mid]<x?L:R)=mid;}return R;}
int upperBound(T)(T[]A,T x){int L=-1,R=cast(int)A.length;while(R-L>1){int mid=(L+R)/2;(A[mid]<=x?L:R)=mid;}return R;}