A lot of nouns ending on soft (palatal(ized)) consonants¹ or vowel /i/ is feminine, eg: noc (night), rzecz (thing), sól (salt), bogini (goddess), cerkiew (gen.sg. cerkwi, Orthodox Church), dłoń (hand)

Virtually all ending on -ść are feminine: miłość (love), kość (bone), ość (fishbone), wysokość (height), maść (ointment, rub), etc.

But there is also a lot of masculine ones: łoś (moose), pajac (pejor. clown, puppet), kac (hangover), koń (horse), stróż (guard), etc.

You can find a pretty good list of those on English Wiktionary, by looking what links to Polish declension of feminine soft consonant nouns template.

¹ ie.: j, ś, sz, ź, ż, rz, c, ć, cz, dź, dz, ń, l (and k, g, m, p, b, f, w when they get additional i in endings, like in cerkiew, cerkwi)

Yep, mysz is feminine, despite the lack of usual ending (-a).

Это правильно, программа должна была принять.