391500+870*450-261*1500-(87945-487957)=391500+391500-391500+400012=791512
391500+870*450--261*1500-(87945-487957)=791512
391500+870*450-261*1500-(87945-487957)=391500+391500-391500+400012=791512
391500+870*450--261*1500-(87945-487957)=791512