Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)
for i in range(edges):
    if not len(nodes[i]):
        dp[i] = 0

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))


Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)
for i in range(edges):
    if not len(nodes[i]):
        dp[i] = 0

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)



print(nodes) 
for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))


Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges+1)]

nodes = [[] for _ in range(edges+1)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)
for i in range(edges):
    if not len(nodes[i]):
        dp[i] = 0

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)



print(nodes) 
for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))


Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges+1)]

nodes = [[] for _ in range(edges+1)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)


def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)



print(nodes) 
for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))


Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(100000)]

nodes = [[] for _ in range(100000)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)


def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)



print(nodes) 
for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))


Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Buggy python submission (verdict: Runtime Error):
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)


def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))

Fixed submission:
import sys
sys.setrecursionlimit(10**6)
edges, vertices = map(int, input().split())
dp = [None for _ in range(edges)]

nodes = [[] for _ in range(edges)]

for i in range(vertices):
    start, end = map(int, input().split())
    nodes[end -1].append(start-1)

def find(arr):
    if not len(arr):
        return 0
    for x in arr:
        if dp[x] is None:
            dp[x] = find(nodes[x])
    return 1 + max(dp[x] for x in arr)

for i in range(edges):
    dp[i] = find(nodes[i])

print(max(dp))