Buggy python submission (verdict: Runtime Error):
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

ctr = 1
Q, K = inpl()
now = [K]
dist = [0 for _ in range(N+1)]
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            dist[nb] = dist[na] + nc
            path[nb].remove((na,nc))
            now.add(nb)
            ctr += 1
    if ctr >=  N:
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])

Fixed submission:
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

ctr = 1
Q, K = inpl()
now = [K]
dist = [0 for _ in range(N+1)]
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            dist[nb] = dist[na] + nc
            path[nb].remove((na,nc))
            now.append(nb)
            ctr += 1
    if ctr >=  N:
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])

Buggy python submission (verdict: Time Limit Exceeded):
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

Q, K = inpl()
now = {K}
dist = [0 for _ in range(N+1)]
visited = [False for _ in range(N+1)]
visited[K] = visited[0] = True
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            dist[nb] = dist[na] + nc
            visited[nb] = True
            path[nb].remove((na,nc))
            now.add(nb)
    if all(visited):
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])

Fixed submission:
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

ctr = 1
Q, K = inpl()
now = [K]
dist = [0 for _ in range(N+1)]
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            dist[nb] = dist[na] + nc
            path[nb].remove((na,nc))
            now.append(nb)
            ctr += 1
    if ctr >=  N:
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])

Buggy python submission (verdict: Time Limit Exceeded):
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

Q, K = inpl()
now = {K}
dist = [0 for _ in range(N+1)]
visited = [False for _ in range(N+1)]
visited[K] = visited[0] = True
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            if visited[nb]:
                continue
            dist[nb] = dist[na] + nc
            visited[nb] = True
            now.add(nb)
    if all(visited):
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])

Fixed submission:
from collections import defaultdict
def inpl(): return [int(i) for i in input().split()]

path = defaultdict(lambda: [])
N = int(input())
for _ in range(N-1):
    a, b, c = inpl()
    path[a].append((b,c))
    path[b].append((a,c))

ctr = 1
Q, K = inpl()
now = [K]
dist = [0 for _ in range(N+1)]
while True:
    for na in now.copy():
        na = now.pop()
        for nb, nc in path[na]:
            dist[nb] = dist[na] + nc
            path[nb].remove((na,nc))
            now.append(nb)
            ctr += 1
    if ctr >=  N:
        break
for i in range(Q):
    x, y = inpl()
    print(dist[x]+dist[y])