Check if specific characters are in a string

I need to find and count how many characters can be found in a string. I have divided the characters into chars1[a:m] and chars2[n:z], and have two counters.

The output should be 0/14, but it is 0/1 instead. I think it only checks to see if one and only one item is contained and then exits out the loop. Is that the case?

Here is the code.

string_1 = "aaabbbbhaijjjm"

def error_printer(s):
    chars1 = "abcdefghijklm"
    chars2 = "nopqrstuvwxyz"
    counter1 = 0
    counter2 = 0

    if ((c in s) for c in chars1):
        counter1 += 1
    elif ((c in s) for c in chars2):
        counter2 += 1
    print(str(counter2) + "/" + str(counter1))

error_printer(string_1)