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

    bn_h = {}
    bn_v = {}

    for i in range(M):
        h, w = map(int, input().split())
        bn_h.setdefault(h, set())
        bn_h[h].add(w)
        bn_v.setdefault(w, set())
        bn_v[w].add(h)

    b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
    b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

    m1 = len(b1[0][1])
    m2 = len(b2[0][1])

    max_result = 0
    for i in b1:
        h, sh = i
        if len(sh) < m1:
            break
        for j in b2:
            v, sv = j
            if len(sv) < m2:
                break
            result = len(sh) + len(sv) - 1
            if h not in sv:
                result += 1
                flag = True
            max_result = max(max_result, result)
            if flag == True:
                break
        if flag == True:
            break
    print(max_result)

if __name__ == '__main__':
    main()

Fixed submission:
import heapq
def main():
    H, W, M = map(int, input().split())

    bn_h = {}
    bn_v = {}

    for i in range(M):
        h, w = map(int, input().split())
        bn_h.setdefault(h, set())
        bn_h[h].add(w)
        bn_v.setdefault(w, set())
        bn_v[w].add(h)

    b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
    b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

    m1 = len(b1[0][1])
    m2 = len(b2[0][1])

    flag = False
    max_result = 0
    for i in b1:
        h, sh = i
        if len(sh) < m1:
            break
        for j in b2:
            v, sv = j
            if len(sv) < m2:
                break
            result = len(sh) + len(sv) - 1
            if h not in sv:
                result += 1
                flag = True
            max_result = max(max_result, result)
            if flag == True:
                break
        if flag == True:
            break
    print(max_result)

if __name__ == '__main__':
    main()

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

    bn_h = {}
    bn_v = {}

    for i in range(M):
        h, w = map(int, input().split())
        bn_h.setdefault(h, set())
        bn_h[h].add(w)
        bn_v.setdefault(w, set())
        bn_v[w].add(h)

    b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
    b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

    m1 = len(b1[0][1])
    m2 = len(b2[0][1])

    max_result = 0
    for i in b1:
        h, sh = i
        if len(sh) < m1:
            break
        for j in b2:
            v, sv = j
            if len(sv) < m2:
                break
            result = len(sh) + len(sv) - 1
            if h not in sv:
                result += 1
            flag = True
            max_result = max(max_result, result)
            if flag = True:
                break
        if flag = True:
            break
    print(max_result)

if __name__ == '__main__':
    main()

Fixed submission:
import heapq
def main():
    H, W, M = map(int, input().split())

    bn_h = {}
    bn_v = {}

    for i in range(M):
        h, w = map(int, input().split())
        bn_h.setdefault(h, set())
        bn_h[h].add(w)
        bn_v.setdefault(w, set())
        bn_v[w].add(h)

    b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
    b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

    m1 = len(b1[0][1])
    m2 = len(b2[0][1])

    flag = False
    max_result = 0
    for i in b1:
        h, sh = i
        if len(sh) < m1:
            break
        for j in b2:
            v, sv = j
            if len(sv) < m2:
                break
            result = len(sh) + len(sv) - 1
            if h not in sv:
                result += 1
                flag = True
            max_result = max(max_result, result)
            if flag == True:
                break
        if flag == True:
            break
    print(max_result)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import heapq

H, W, M = map(int, input().split())

bn_h = {}
bn_v = {}

for i in range(M):
    h, w = map(int, input().split())
    bn_h.setdefault(h, set())
    bn_h[h].add(w)
    bn_v.setdefault(w, set())
    bn_v[w].add(h)

b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

m1 = len(b1[0][1])
m2 = len(b2[0][1])

max_result = 0
for i in b1:
    h, sh = i
    if len(sh) < m1:
        break
    for j in b2:
        v, sv = j
        if len(sv) < m2:
            break
        result = len(sh) + len(sv) - 1
        if h not in sv:
            result += 1
        max_result = max(max_result, result)
print(max_result)


Fixed submission:
import heapq
def main():
    H, W, M = map(int, input().split())

    bn_h = {}
    bn_v = {}

    for i in range(M):
        h, w = map(int, input().split())
        bn_h.setdefault(h, set())
        bn_h[h].add(w)
        bn_v.setdefault(w, set())
        bn_v[w].add(h)

    b1 = sorted(bn_h.items(), key = lambda x:len(x[1]), reverse=True)
    b2 = sorted(bn_v.items(), key = lambda x:len(x[1]), reverse=True)

    m1 = len(b1[0][1])
    m2 = len(b2[0][1])

    flag = False
    max_result = 0
    for i in b1:
        h, sh = i
        if len(sh) < m1:
            break
        for j in b2:
            v, sv = j
            if len(sv) < m2:
                break
            result = len(sh) + len(sv) - 1
            if h not in sv:
                result += 1
                flag = True
            max_result = max(max_result, result)
            if flag == True:
                break
        if flag == True:
            break
    print(max_result)

if __name__ == '__main__':
    main()