Buggy python submission (verdict: Runtime Error):
from collections import deque

N = int(input())
X = [list(map(int, input().split())) for _ in range(N)]

graph = [[] for _ in range(N * N)]
ins = [0] * (N * N)

for i, nodes in enumerate(X):
    for j1, j2 in zip(nodes[:-1], nodes[1:]):
        n1 = max(i, j1 - 1) * N + min(i, j1 - 1)
        n2 = max(i, j2 - 1) * N + min(i, j2 - 1)
        graph[n1].append(n2)
        ins[n2] += 1

dist = [0] * (N * N)
visited = [False] * (N * N)
q = deque()
for i in range(N):
    visited[N * i + i] = True

for i, v in enumerate(ins):
    if v == 0:
        q.append(i)
        visited[i] = True
        dist[i] = 1

while q:
    u = q.popleft()
    for v in graph[u]:
        if visited[v]:
            continue

        ins[v] -= 1
        if ins[v] == 0:
            visited[v] = True
            dist[v] = dist[u] + 1
            q.append(v)
            
print(max(dist) if all(visited) else -1)



Fixed submission:
N, *B = map(int, open(0).read().split())

ans = B[0] + B[-1]
for i in range(N - 2):
    ans += min(B[i], B[i + 1])
    
print(ans)

Buggy python submission (verdict: Runtime Error):
from collections import deque

N = int(input())
X = [list(map(int, input().split())) for _ in range(N)]

graph = [[] for _ in range(N * N)]
ins = [0] * (N * N)

for i, nodes in enumerate(X):
    for j1, j2 in zip(nodes[:-1], nodes[1:]):
        n1 = max(i, j1 - 1) * N + min(i, j1 - 1)
        n2 = max(i, j2 - 1) * N + min(i, j2 - 1)
        graph[n1].append(n2)
        ins[n2] += 1

dist = [0] * (N * N)
visited = [False] * (N * N)
q = deque()
for i in range(N):
    visited[N * i + i] = True

for i, v in enumerate(ins):
    if v == 0:
        q.append(i)
        visited[i] = True
        dist[i] = 1

while q:
    u = q.popleft()
    for v in graph[u]:
        if visited[v]:
            continue

        ins[v] -= 1
        if ins[v] == 0:
            visited[v] = True
            dist[v] = dist[u] + 1
            q.append(v)
            
print(max(dist) if all(visited) else -1)



Fixed submission:
N, *B = map(int, open(0).read().split())

ans = B[0] + B[-1]
for i in range(N - 2):
    ans += min(B[i], B[i + 1])
    
print(ans)

Buggy python submission (verdict: Runtime Error):
from collections import deque

N = int(input())
X = [list(map(int, input().split())) for _ in range(N)]

graph = [[] for _ in range(N * N)]
ins = [0] * (N * N)

for i, nodes in enumerate(X):
    for j1, j2 in zip(nodes[:-1], nodes[1:]):
        n1 = max(i, j1 - 1) * N + min(i, j1 - 1)
        n2 = max(i, j2 - 1) * N + min(i, j2 - 1)
        graph[n1].append(n2)
        ins[n2] += 1

dist = [0] * (N * N)
visited = [False] * (N * N)
q = deque()
for i in range(N):
    visited[N * i + i] = True

for i, v in enumerate(ins):
    if v == 0:
        q.append(i)
        visited[i] = True
        dist[i] = 1

while q:
    u = q.popleft()
    for v in graph[u]:
        if visited[v]:
            continue

        ins[v] -= 1
        if ins[v] == 0:
            visited[v] = True
            dist[v] = dist[u] + 1
            q.append(v)
            
print(max(dist) if all(visited) else -1)



Fixed submission:
N, *B = map(int, open(0).read().split())

ans = B[0] + B[-1]
for i in range(N - 2):
    ans += min(B[i], B[i + 1])
    
print(ans)