Buggy python submission (verdict: Runtime Error):
import sys

H, W, M = map(int, input().split())
hw = [list(map(int, input().split())) for _ in range(M)]

hw.sort()

hcnt = [0] * (H+1)
wcnt = [0] * (W+1)

target = []
for i, j in hw:
    hcnt[i] += 1
    wcnt[j] += 1
    target.append([str(i) + " " + str(j),1])

d = dict(target)

hlist = []
hmax = -1
for i in range(1,H+1):
    if hmax < hcnt[i]:
        hlist = [i]
        hmax = hcnt[i]
    elif hmax == hcnt[i]:
        hlist.append(i)

wlist = []
wmax = -1
for i in range(1,W+1):
    if wmax < wcnt[i]:
        wlist = [i]
        wmax = wcnt[i]
    elif wmax == wcnt[i]:
        wlist.append(i)

if len(hlist) * len(wlist) > M:
    print(hmax + wmax)
    sys.exit()

idx = 0
for h in hlist:
    for w in wlist:
        while h > hw[idx][0] or w > hw[idx][1]:
            idx += 1
            if h == hw[idx][0] and w == hw[idx][1]:
                break
        if h < hw[idx][0] or w < hw[idx][1]:
            print(hmax + wmax)
            sys.exit()
        
print(hmax + wmax - 1)


Fixed submission:
import sys

H, W, M = map(int, input().split())
hw = [list(map(int, input().split())) for _ in range(M)]

hw.sort()

hcnt = [0] * (H+1)
wcnt = [0] * (W+1)

target = []
for i, j in hw:
    hcnt[i] += 1
    wcnt[j] += 1
    target.append([str(i) + " " + str(j),1])

d = dict(target)

hlist = []
hmax = -1
for i in range(1,H+1):
    if hmax < hcnt[i]:
        hlist = [i]
        hmax = hcnt[i]
    elif hmax == hcnt[i]:
        hlist.append(i)

wlist = []
wmax = -1
for i in range(1,W+1):
    if wmax < wcnt[i]:
        wlist = [i]
        wmax = wcnt[i]
    elif wmax == wcnt[i]:
        wlist.append(i)

if len(hlist) * len(wlist) > M:
    print(hmax + wmax)
    sys.exit()

idx = 0
for h in hlist:
    for w in wlist:
        while h > hw[idx][0] or w > hw[idx][1]:
            idx += 1
            if idx == M:
                print(hmax + wmax)
                sys.exit()                
            if h == hw[idx][0] and w == hw[idx][1]:
                break
        if h < hw[idx][0] or w < hw[idx][1]:
            print(hmax + wmax)
            sys.exit()
        
print(hmax + wmax - 1)

Buggy python submission (verdict: Runtime Error):
import sys

H, W, M = map(int, input().split())
hw = [list(map(int, input().split())) for _ in range(M)]

hw.sort()

hcnt = [0] * (H+1)
wcnt = [0] * (W+1)

target = []
for i, j in hw:
    hcnt[i] += 1
    wcnt[j] += 1
    target.append([str(i) + " " + str(j),1])

d = dict(target)

hlist = []
hmax = -1
for i in range(1,H+1):
    if hmax < hcnt[i]:
        hlist = [i]
        hmax = hcnt[i]
    elif hmax == hcnt[i]:
        hlist.append(i)

wlist = []
wmax = -1
for i in range(1,W+1):
    if wmax < wcnt[i]:
        wlist = [i]
        wmax = wcnt[i]
    elif wmax == wcnt[i]:
        wlist.append(i)

if len(hlist) * len(wlist) > M:
    print(hmax + wmax)
    sys.exit()

idx = 0
for h in hlist:
    for w in wlist:
        while h > hw[idx][0] or w > hw[idx][1]:
            idx += 1
            if h == hw[idx][0] and w == hw[idx][1]:
                break
        if h < hw[idx][0] or w < hw[idx][1]:
            print(hmax + wmax)
            sys.exit()
        
print(hmax + wmax - 1)

Fixed submission:
import sys

H, W, M = map(int, input().split())
hw = [list(map(int, input().split())) for _ in range(M)]

hw.sort()

hcnt = [0] * (H+1)
wcnt = [0] * (W+1)

target = []
for i, j in hw:
    hcnt[i] += 1
    wcnt[j] += 1
    target.append([str(i) + " " + str(j),1])

d = dict(target)

hlist = []
hmax = -1
for i in range(1,H+1):
    if hmax < hcnt[i]:
        hlist = [i]
        hmax = hcnt[i]
    elif hmax == hcnt[i]:
        hlist.append(i)

wlist = []
wmax = -1
for i in range(1,W+1):
    if wmax < wcnt[i]:
        wlist = [i]
        wmax = wcnt[i]
    elif wmax == wcnt[i]:
        wlist.append(i)

if len(hlist) * len(wlist) > M:
    print(hmax + wmax)
    sys.exit()

idx = 0
for h in hlist:
    for w in wlist:
        while h > hw[idx][0] or w > hw[idx][1]:
            idx += 1
            if idx == M:
                print(hmax + wmax)
                sys.exit()                
            if h == hw[idx][0] and w == hw[idx][1]:
                break
        if h < hw[idx][0] or w < hw[idx][1]:
            print(hmax + wmax)
            sys.exit()
        
print(hmax + wmax - 1)