Buggy python submission (verdict: Runtime Error):
import sys
import random
H,W,M=map(int,input().split())

hlist=[0]*H
wlist=[0]*W
hwset=set()
for _ in range(M):
  h,w=map(int,input().split())
  hlist[h-1]+=1
  wlist[w-1]+=1
  hwset.add((h-1,w-1))
  
hmax=max(hlist)
wmax=max(wlist)

hlist2=[]
for i in range(H):
  if hlist[i]==hmax:
    hlist2.append(i)
hlist2.sort(reverse=True)
random.shuffle(hlist2)

wlist2=[]
for i in range(W):
  if wlist[i]==wmax:
    wlist2.append(i)
wlist2.sort(reverse=True)
random.shuffle(wlist2)

#print(hlist2,wlist2)
H2=len(hlist2)
W2=len(wlist2)

if H2*W2>10**7:
  norm=(H2*W2)//(10**7)+1
  H2=int(H2/(norm**0.5))
  W2=int(W2/(norm**0.5))

for i in range(H2):
  ii=hlist2[i]
  for j in range(W2):
    jj=wlist2[j]
    if not (ii,jj) in hwset:
      print(hh+ww)
      sys.exit(0)
else:
  print(hmax+wmax-1)

Fixed submission:
import sys
import random
H,W,M=map(int,input().split())

hlist=[0]*H
wlist=[0]*W
hwset=set()
for _ in range(M):
  h,w=map(int,input().split())
  hlist[h-1]+=1
  wlist[w-1]+=1
  hwset.add((h-1,w-1))
  
hmax=max(hlist)
wmax=max(wlist)

hlist2=[]
for i in range(H):
  if hlist[i]==hmax:
    hlist2.append(i)
hlist2.sort(reverse=True)
random.shuffle(hlist2)

wlist2=[]
for i in range(W):
  if wlist[i]==wmax:
    wlist2.append(i)
wlist2.sort(reverse=True)
random.shuffle(wlist2)

#print(hlist2,wlist2)
H2=len(hlist2)
W2=len(wlist2)

if H2*W2>=10**7:
  norm=(H2*W2)//(10**7)
  H2=int(H2/(norm**0.5))
  W2=int(W2/(norm**0.5))

for i in range(H2):
  ii=hlist2[i]
  for j in range(W2):
    jj=wlist2[j]
    if not (ii,jj) in hwset:
      print(hmax+wmax)
      sys.exit(0)
else:
  print(hmax+wmax-1)

Buggy python submission (verdict: Runtime Error):
import sys
import random
H,W,M=map(int,input().split())

hlist=[0]*H
wlist=[0]*W
hwset=set()
for _ in range(M):
  h,w=map(int,input().split())
  hlist[h-1]+=1
  wlist[w-1]+=1
  hwset.add((h-1,w-1))
  
hmax=max(hlist)
wmax=max(wlist)

hlist2=[]
for i in range(H):
  if hlist[i]==hmax:
    hlist2.append(i)
hlist2.sort(reverse=True)
random.shuffle(hlist2)

wlist2=[]
for i in range(W):
  if wlist[i]==wmax:
    wlist2.append(i)
wlist2.sort(reverse=True)
random.shuffle(wlist2)

#print(hlist2,wlist2)
H2=len(hlist2)
W2=len(wlist2)

if H2*W2>10**7:
  norm=(H2*W2)//(10**7)
  H2=int(H2/(norm**0.5))
  W2=int(W2/(norm**0.5))

for i in range(H2):
  ii=hlist2[i]
  for j in range(W2):
    jj=wlist2[j]
    if not (ii,jj) in hwset:
      print(hh+ww)
      sys.exit(0)
else:
  print(hmax+wmax-1)

Fixed submission:
import sys
import random
H,W,M=map(int,input().split())

hlist=[0]*H
wlist=[0]*W
hwset=set()
for _ in range(M):
  h,w=map(int,input().split())
  hlist[h-1]+=1
  wlist[w-1]+=1
  hwset.add((h-1,w-1))
  
hmax=max(hlist)
wmax=max(wlist)

hlist2=[]
for i in range(H):
  if hlist[i]==hmax:
    hlist2.append(i)
hlist2.sort(reverse=True)
random.shuffle(hlist2)

wlist2=[]
for i in range(W):
  if wlist[i]==wmax:
    wlist2.append(i)
wlist2.sort(reverse=True)
random.shuffle(wlist2)

#print(hlist2,wlist2)
H2=len(hlist2)
W2=len(wlist2)

if H2*W2>=10**7:
  norm=(H2*W2)//(10**7)
  H2=int(H2/(norm**0.5))
  W2=int(W2/(norm**0.5))

for i in range(H2):
  ii=hlist2[i]
  for j in range(W2):
    jj=wlist2[j]
    if not (ii,jj) in hwset:
      print(hmax+wmax)
      sys.exit(0)
else:
  print(hmax+wmax-1)