#!/usr/bin/env python3

lines = (list(map(int, x.strip().split(','))) for x in open("input.txt"))

for line in lines:
    line.sort()
    mean = round(sum(line) / len(line))
    # fix of by one error
    print(min(sum(abs(x - m)*(abs(x - m)+1)//2 for x in line) for m in range(mean-1, mean+2)))