679 B | 679 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
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 solve():
n, m, k = mii()
l = [mii() for _ in range(k)]
target = [1, m + 1]
ans = -1
mn = 11111111111111
for i in range(k):
y, x = l[i]
dis = abs(target[0] - y) + abs(target[1] - x)
if dis < mn:
mn = dis
ans = i + 1
p(ans)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()