How many years after Alexander the great defeated King Porus during his invasion of Pauravas did the Indo-Greek Kingdom form?
return Alexander the  great defeated King Porus during his invasion of Pauravas ;return the  Indo-Greek Kingdom did form ;return year of #1 ;return year of #2 ;return difference of #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']