744 B | 744 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
BLANK = " "
inp = input
# inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def sign(a):
return a < 0
def solve():
W, H, N = mii()
a, b = mii()
k = 0
for _ in range(N - 1):
x, y = mii()
if sign(x - a) == sign(y - b):
i = abs(x - a)
j = abs(y - b)
k += max(i, j)
else:
k += abs(x - a) + abs(y - b)
a = x
b = y
p(k)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()