import argparse
import functools

parser = argparse.ArgumentParser()
parser.add_argument("ifile", type=argparse.FileType('r'))
args = parser.parse_args()
crabs = [int(x) for x in args.ifile.readline().split(',')]

def sumOfSeq(start: int, end: int) -> int:
    #  n⁄2 {2a + (n − 1) d}
    n = end
    d = 1
    return int(n * (2 * start + (n - 1)) / 2)


print(min([sum([sumOfSeq(1, abs(start - pos)) for start in crabs]) for pos in range(0, len(crabs) + 1)]))