20 students stood in a line. Jungkook stood last in line, and Yoongi stood right in front of Jungkook. How many students are 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))