If an elevator starts at 120 meters (m) above the ground and descends at a speed of 4 meters (m) per second without stopping once, find the height of the elevator 20 seconds after starting in meters (m).
120 4 20 [OP_MUL] [OP_SUB]
var_a = 120
var_b = 4
var_c = 20
var_d = var_b * var_c
var_e = var_a - var_d
print(int(var_e))