#!/usr/bin/env python


def read_input():
    result = []
    with open('input.txt', 'r') as f:
        for line in f:
            result.append([ int(x) for x in line.split(', ')])
    return result

MARGIN=10000
coord = read_input()
coord_min = [ min([x[0] for x in coord]), min([x[1] for x in coord]) ]
coord_max = [ max([x[0] for x in coord]), max([x[1] for x in coord]) ]

area_size = 0
for x in range(coord_max[0]-MARGIN-1, coord_min[0]+MARGIN+1):
    for y in range(coord_max[1]-MARGIN-1, coord_min[1]+MARGIN+1):

       d_total = 0
       for loc in  coord:
           if d_total >= MARGIN:
               break
           d_total = d_total + abs(x - loc[0]) + abs(y - loc[1])
       else:
           if d_total < MARGIN:
               area_size += 1

print(area_size)