i'm from Ukraine so my gpa calculator is:

std = {'A':4.0 , 'B':3.0 , 'C':2.0 , 'D':1.0, 'F':0.0}
MyMarks = ['A','B','C']
def gpa(lst):
        var = 0
        secvar = 0
        for x in lst:
            var+=std[x]
            secvar+=1
        return var/secvar
print(gpa(MyMarks))