Buggy python submission (verdict: Time Limit Exceeded):
N, M = [int(i) for i in input().split()]
Groups = [[i] for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2].extend(Groups[src2])
    Groups[src2] = []
    # print(Groups)
    # print(dsts)
ans = 0
for group in Groups:
    ans = max(ans, len(group))
print(ans)


Fixed submission:
N, M = [int(i) for i in input().split()]
Groups = [1 for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2] += Groups[src2]
    Groups[src2] = 0
    # print(Groups)
    # print(dsts)
print(max(Groups))

Buggy python submission (verdict: Time Limit Exceeded):
N, M = [int(i) for i in input().split()]
Groups = [[i] for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        dsts[min(A, B)] = dst
    if src != max(A, B):
        dsts[max(A, B)] = src

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2].extend(Groups[src2])
    Groups[src2] = []
    # print(Groups)
    # print(dsts)
ans = 0
for group in Groups:
    ans = max(ans, len(group))
print(ans)


Fixed submission:
N, M = [int(i) for i in input().split()]
Groups = [1 for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2] += Groups[src2]
    Groups[src2] = 0
    # print(Groups)
    # print(dsts)
print(max(Groups))

Buggy python submission (verdict: Time Limit Exceeded):
N, M = [int(i) for i in input().split()]
Groups = [[i] for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2].extend(Groups[src2])
    Groups[src2] = []
    # print(Groups)
    # print(dsts)
ans = 0
for group in Groups:
    ans = max(ans, len(group))
print(ans)


Fixed submission:
N, M = [int(i) for i in input().split()]
Groups = [1 for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2] += Groups[src2]
    Groups[src2] = 0
    # print(Groups)
    # print(dsts)
print(max(Groups))

Buggy python submission (verdict: Time Limit Exceeded):
N, M = [int(i) for i in input().split()]
Groups = [[i] for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst == src:
        continue
    dsts[src] = dst
    Groups[dst].extend(Groups[src])
    Groups[src] = []
    # print(Groups)
    # print(dsts)
ans = 0
for group in Groups:
    ans = max(ans, len(group))
print(ans)


Fixed submission:
N, M = [int(i) for i in input().split()]
Groups = [1 for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2] += Groups[src2]
    Groups[src2] = 0
    # print(Groups)
    # print(dsts)
print(max(Groups))

Buggy python submission (verdict: Time Limit Exceeded):
N, M = [int(i) for i in input().split()]
Groups = [{i} for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst == src:
        continue
    dsts[src] = dst
    Groups[dst] = Groups[dst] | Groups[src]
    Groups[src] = {}
    # print(Groups)
    # print(dsts)
ans = 0
for group in Groups:
    ans = max(ans, len(group))
print(ans)


Fixed submission:
N, M = [int(i) for i in input().split()]
Groups = [1 for i in range(N)]
dsts = [-1 for i in range(N)]
ABs = [[int(i)-1 for i in input().split()] for i in range(M)]
for A, B in ABs:
    dst = min(A, B)
    src = max(A, B)
    # print('A', A, B, dst, src)
    while(dsts[dst] != -1):
        dst = dsts[dst]
    while(dsts[src] != -1):
        src = dsts[src]
    if dst != min(A, B):
        omdst = min(A, B)
        while(dsts[omdst] != dst):
            n_omdst = dsts[omdst]
            dsts[omdst] = dst
            omdst = n_omdst
    if src != max(A, B):
        omsrc = max(A, B)
        while(dsts[omsrc] != src):
            n_omsrc = dsts[omsrc]
            dsts[omsrc] = src
            omsrc = n_omsrc

    if dst == src:
        continue
    dst2 = min(dst, src)
    src2 = max(dst, src)
    dsts[src2] = dst2
    Groups[dst2] += Groups[src2]
    Groups[src2] = 0
    # print(Groups)
    # print(dsts)
print(max(Groups))