import std.stdio, std.algorithm, std.array, std.conv, std.string;

bool[10100] dp;

void main()
{
    readln();
    auto ws = readln().split().map!(to!int);
    long sum = 0;
    dp[0] = true;
    foreach(w; ws) {
        sum += w;
        foreach_reverse(i; 0..10001) {
            if (dp[i]) dp[i + w] = true;
        }
    }
    if (sum % 2 == 0 && dp[sum/2]) writeln("possible");
    else writeln("impossible");
}