Code:
class 𝖼𝗅𝖺𝗌𝗌 {
public static void main(String[] args) {
System.out.println("Hello, world!");
}
}
name it 𝖼𝗅𝖺𝗌𝗌.java and compile.
It exploits Unicode homographs (like c to U+1D5BC MATHEMATICAL SANS-SERIF SMALL C), but some homographs are normalized in International Domain Names (IDNs) to prevent phishing.
