Advent of code - Day 2 - Second task

combination_rock_A = {"Y": 4, "X": 3, "Z": 8}
combination_paper_B = {"Y": 5, "X": 1, "Z": 9}
combination_scissor_C = {"Y": 6, "X": 2, "Z": 7}

my_sum = 0

with open("input_data.txt", "r") as file:
    for line in file.readlines():
        my_char = line[2]
        if line[0] == "A":
            my_sum += combination_rock_A[my_char]
        elif line[0] == "B":
            my_sum += combination_paper_B[my_char]
        elif line[0] == 'C':
            my_sum += combination_scissor_C[my_char]

print(my_sum)