Emergency litter substitute?

this has never happened to me before & this is my first time really having a pet so i'm usually extra cautious and on top of these things regardless of my less than ideal financial situation. i was changing her litter and mistakenly thought i had more than i do and unfortunately i don't have enough to actually even take the bus/train and get to the store let alone buy more litter. what can i use in the meantime until i'm able to go and get more? I'm hoping it won't be longer than a few days at most. her name is mouse and she just turned 6 months and i love her<3