fetch -o - http://eval.dan.co.jp/friends/2026/11/08/d6fb56edb3116f83c8a126758578da4ffdd82fb9b513ba530020f929cc5bda20 | sed 's/(P[[]0[]],)/(P[-1],)/;s/cons(sm(P[[]i[]],R[[]0[]])/cons(sm(P[-1-i],R[0])/' | sh