How many functions whose derivative is {{MATH_32}} are there? {{CMD_33}} {{CMD_34}} {{CMD_35}}Zero{{CMD_36}} {{CMD_37}}One{{CMD_38}} {{CMD_39}}Two{{CMD_40}} {{CMD_41}}Three{{CMD_42}} {{CMD_43}}Four{{CMD_44}} {{CMD_45}}Infinitely many{{CMD_46}} {{CMD_47}} {{CMD_48}} {{CMD_49}}