Otto cycle consists of following four processes
Two isothermals and two isentropic
Two isentropic and two constant volumes
Two isentropic, one constant volume and one constant pressure
Two isentropic and two constant pressures
Two isothermals and two isentropic
Two isentropic and two constant volumes
Two isentropic, one constant volume and one constant pressure
Two isentropic and two constant pressures