import std.stdio;
import std.range;
import std.array;
import std.algorithm;
import std.string;
import std.conv;
import std.typecons;
import std.math;
import std.numeric;

void main() {
    int[] input;
    foreach (i; 0 .. 5) {
        input ~= readln().chomp().to!int;
    }
    immutable k = readln().chomp().to!int;

    solve(input, k).writeln();
}

string solve(int[] antennas, int distance) {
    auto result = true;

    foreach (i, antenna; antennas) {
        foreach (other; antennas[i + 1 .. $]) {
            if (other - antenna > distance) {
                result = false;
                break;
            }
            if (!result) {
                break;
            }
        }
    }

    if (result) {
        return "Yay!";
    }
    else {
        return ":(";
    }
}

unittest {
    assert(solve([1, 2, 4, 8, 9], 15) == "Yay!");
    assert(solve([15, 18, 26, 35, 36], 18) == ":(");
}
