20 students were lined up, and Jungkook took the first place in the line. Yoongi stood right behind Jungkook. Find the number of students standing behind Yoongi.
20 1 [OP_SUB] 1 [OP_SUB]
var_a = 20
var_b = 1
var_c = var_a - var_b
var_d = 1
var_e = var_c - var_d
print(int(var_e))