Buggy python submission (verdict: Runtime Error):
import sys
from collections import defaultdict
sys.setrecursionlimit(100000)

N, M = map(int, input().split())
AB = defaultdict(list)
gain = [0]*N
for i in range(N + M - 1):
    a, b = map(int, input().split())
    AB[a - 1].append(b - 1)
    gain[b - 1] += 1

ans = [None]*N
def rec(u, p):
    ans[u] = p
    for v in AB[u]:
        gain[v] -= 1
    for v in AB[u]:
        if gain[v] == 0 and ans[v] is None:
            rec(v, u)

root = gain.index(0)
rec(root, -1)

for i in range(N):
    print(ans[i] + 1)


Fixed submission:
import sys
from collections import defaultdict
sys.setrecursionlimit(100000)

N, M = map(int, input().split())
AB = []
D = defaultdict(lambda: [])
for i in range(N + M - 1):
    a, b = map(int, input().split())
    AB.append((a - 1, b - 1))
    D[a - 1].append(b - 1)

z = [0]*N
for a, b in AB:
    z[b] += 1

ans = [-1]*N
root = z.index(0)
ok = [False]*N
def rec(u, p):
    ans[u] = p
    ok[u] = True
    for v in D[u]:
        z[v] -= 1
    for v in D[u]:
        if z[v] == 0 and not ok[v]:
            rec(v, u)


rec(root, -1)

for i in range(N):
    print(ans[i] + 1)

Buggy python submission (verdict: Runtime Error):
import sys
from collections import defaultdict
sys.setrecursionlimit(100000)

N, M = map(int, input().split())
D = defaultdict(lambda: [])
gain = [0]*N
for i in range(N + M - 1):
    a, b = map(int, input().split())
    D[a - 1].append(b - 1)
    gain[b - 1] += 1

ans = [None]*N
def rec(u, p):
    ans[u] = p
    for v in D[u]:
        gain[v] -= 1
    for v in D[u]:
        if gain[v] == 0 and ans[v] is None:
            rec(v, u)

root = gain.index(0)
rec(root, -1)

for i in range(N):
    print(ans[i] + 1)


Fixed submission:
import sys
from collections import defaultdict
sys.setrecursionlimit(100000)

N, M = map(int, input().split())
AB = []
D = defaultdict(lambda: [])
for i in range(N + M - 1):
    a, b = map(int, input().split())
    AB.append((a - 1, b - 1))
    D[a - 1].append(b - 1)

z = [0]*N
for a, b in AB:
    z[b] += 1

ans = [-1]*N
root = z.index(0)
ok = [False]*N
def rec(u, p):
    ans[u] = p
    ok[u] = True
    for v in D[u]:
        z[v] -= 1
    for v in D[u]:
        if z[v] == 0 and not ok[v]:
            rec(v, u)


rec(root, -1)

for i in range(N):
    print(ans[i] + 1)

Buggy python submission (verdict: Runtime Error):
from collections import defaultdict
N, M = map(int, input().split())
AB = []
D = defaultdict(lambda: [])
for i in range(N + M - 1):
    a, b = map(int, input().split())
    AB.append((a - 1, b - 1))
    D[a - 1].append(b - 1)

z = [0]*N
for a, b in AB:
    z[b] += 1

ans = [-1]*N
root = z.index(0)
ok = [False]*N
def rec(u, p):
    ans[u] = p
    ok[u] = True
    for v in D[u]:
        z[v] -= 1
    for v in D[u]:
        if z[v] == 0 and not ok[v]:
            rec(v, u)


rec(root, -1)

for i in range(N):
    print(ans[i] + 1)


Fixed submission:
import sys
from collections import defaultdict
sys.setrecursionlimit(100000)

N, M = map(int, input().split())
AB = []
D = defaultdict(lambda: [])
for i in range(N + M - 1):
    a, b = map(int, input().split())
    AB.append((a - 1, b - 1))
    D[a - 1].append(b - 1)

z = [0]*N
for a, b in AB:
    z[b] += 1

ans = [-1]*N
root = z.index(0)
ok = [False]*N
def rec(u, p):
    ans[u] = p
    ok[u] = True
    for v in D[u]:
        z[v] -= 1
    for v in D[u]:
        if z[v] == 0 and not ok[v]:
            rec(v, u)


rec(root, -1)

for i in range(N):
    print(ans[i] + 1)