Task: Question Generation
Input (English): #1 return the  start of the First Goryeo-Khitan War 
#2 return King Seongjong dies 
#3 return year of #1 
#4 return year of #2 
#5 return the  difference of #4 and  #3
Output (English): How many years after the start of the First Goryeo-Khitan War did King Seongjong die?