If you give 6 snacks to each of the 18 students, it's left, and if you give 7 snacks to each student, it's not enough. What is the maximum number of snacks?
18 7 [OP_MUL] 1 [OP_SUB]
var_a = 18
var_b = 7
var_c = var_a * var_b
var_d = 1
var_e = var_c - var_d
print(int(var_e))