Yeonseo has more than two types of skirts and pants each. If there are 4 types of pants and 7 ways to choose pants or skirts, find the number of cases that Yeonseo chooses a skirt.
7 4 [OP_SUB]
var_a = 7
var_b = 4
var_c = var_a - var_b
print(int(var_c))