open Array
let a=make 60""let rec($)i?(c=input_char stdin)j=c='
'&0$j+1;a.(50+i+j)<-Printf.sprintf"%*s%c"(i*2-j*2)a.(50+i+j)c;i-1$j;;try 0$0with _->map(fun s->s>""&()=print_endline s;s)a=a