from itertools import islice

with open('pi-hex.1000000.txt', 'r') as f:
    pi = (int(i, 16) for i in f.read())


ndigits = int('31415', 16)
result = sum(i for i in islice(pi, ndigits) if i % 2 == 1)

print(f'Sum of first {hex(ndigits)}={ndigits} digits of pi (in hex) = {hex(result)}={result}.')