情報オリンピック 問題1

gistfile1.txt

rdat(Fn) :-  see(Fn),
	readln([X0]),
	assert(pasta(X0)),
	readln([X1]),
	assert(pasta(X1)),
	readln([X2]),
	assert(pasta(X2)),
	readln([X3]),
	assert(juice(X3)),
	readln([X4]),
	assert(juice(X4)),
	seen.

set_menu(RES) :- pasta(P), juice(J), Set is P + J - 50, set_menu(Set, RES).
set_menu(Rset, RES) :- pasta(P), juice(J), Set is P + J - 50, 
	Set < Rset, !, set_menu(Set, RES).
set_menu(Rset, Rset).

?- rdat('no1-3.dat'), set_menu(X), write(X).