You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named N-[[1-[2-[butyl(methyl)amino]-2-oxoethyl]benzimidazol-2-yl]methyl]-2-fluorobenzamide by IUPAC nomenclature, provide its molecular formula.
user
C22H25FN4O2
assistant