Buggy python submission (verdict: Runtime Error):
n = int(input())
testimony_table = [[] for _ in range(n)]

for i_witness in range(n):
    ai = int(input())
    for _ in range(ai):
        xij, yij= map(int, input().split())
        testimony_table[i_witness].append((xij-1,yij))

ans = 0
for i in range(2**n):
    isConflict = False

    for j_witness in range(n): # それぞれの桁について0か1かを判断したいので
        if (i >> j_witness) & 1 == 0: # j桁目が1かどうかをジャッジ
            continue


        for x_suspect, y_testimony in testimony_table[j_witness]:
            if ((i >> x_suspect) & 1) != y_testimony:
                isConflict = True
                break

        if isConflict:
            break
    if isConflict == False:
        ans = max(ans, bin(i).count("1"))

print(ans)




Fixed submission:
n = int(input())
x = list( map(int, input().split()))


def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

def mod_inv(a,mod):
    x = extgcd(a,mod)[0]
    return (mod+x%mod)%mod

ans = 0
MOD = 10**9 + 7

factorial = 1
for i in range(2,n):
    factorial = (factorial * i%MOD) %MOD

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + factorial*mod_inv(i+1,MOD)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])%MOD*p[i]
    ans %= MOD

print(int(ans))

Buggy python submission (verdict: Runtime Error):
import math

n = int(input())
x = list( map(int, input().split()))

ans = 0
MOD = 10**9 + 7

factorial = math.factorial(n-1)

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + (factorial/(i+1))%MOD
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])*p[i]
    ans %= MOD

ans %= MOD

print(int(ans))

Fixed submission:
n = int(input())
x = list( map(int, input().split()))


def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

def mod_inv(a,mod):
    x = extgcd(a,mod)[0]
    return (mod+x%mod)%mod

ans = 0
MOD = 10**9 + 7

factorial = 1
for i in range(2,n):
    factorial = (factorial * i%MOD) %MOD

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + factorial*mod_inv(i+1,MOD)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])%MOD*p[i]
    ans %= MOD

print(int(ans))

Buggy python submission (verdict: Runtime Error):
import math

n = int(input())
x = list( map(int, input().split()))

ans = 0
MOD = 10**9 + 7

fact = math.factorial(n-1)

p = [0]*(n-1)
p[0] = 1 * fact%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + (fact/(i+1))%MOD
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])*p[i]
    ans %= MOD

ans %= MOD

print(int(ans))


Fixed submission:
n = int(input())
x = list( map(int, input().split()))


def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

def mod_inv(a,mod):
    x = extgcd(a,mod)[0]
    return (mod+x%mod)%mod

ans = 0
MOD = 10**9 + 7

factorial = 1
for i in range(2,n):
    factorial = (factorial * i%MOD) %MOD

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + factorial*mod_inv(i+1,MOD)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])%MOD*p[i]
    ans %= MOD

print(int(ans))

Buggy python submission (verdict: Runtime Error):
import math

n = int(input())
x = list( map(int, input().split()))

ans = 0
MOD = 10**9 + 7

p = [0]*(n-1)
p[0] = 1 * math.factorial(n-1)
for i in range(1,n-1):
    p[i] = p[i-1] + math.factorial(n-1)/(i+1)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])*p[i]
    ans %= MOD

ans %= MOD

print(int(ans))

Fixed submission:
n = int(input())
x = list( map(int, input().split()))


def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

def mod_inv(a,mod):
    x = extgcd(a,mod)[0]
    return (mod+x%mod)%mod

ans = 0
MOD = 10**9 + 7

factorial = 1
for i in range(2,n):
    factorial = (factorial * i%MOD) %MOD

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + factorial*mod_inv(i+1,MOD)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])%MOD*p[i]
    ans %= MOD

print(int(ans))

Buggy python submission (verdict: Runtime Error):
import math
import numpy as np

n = int(input())
x = list( map(int, input().split()))

x = np.array(x)

dist = x[1:] - x[:-1]

ans = 0
MOD = 10**9 + 7

p = [0]*(n-1)
p[0] = 1 * math.factorial(n-1)
for i in range(1,n-1):
    p[i] = p[i-1] + math.factorial(n-1)/(i+1)
    p[i] %= MOD

for i in range(n-1):
    ans += dist[i]*p[i]
    ans %= MOD

ans %= MOD

print(int(ans))

Fixed submission:
n = int(input())
x = list( map(int, input().split()))


def extgcd(a,b):
    r = [1,0,a]
    w = [0,1,b]
    while w[2]!=1:
        q = r[2]//w[2]
        r2 = w
        w2 = [r[0]-q*w[0],r[1]-q*w[1],r[2]-q*w[2]]
        r = r2
        w = w2
    #[x,y]
    return [w[0],w[1]]

def mod_inv(a,mod):
    x = extgcd(a,mod)[0]
    return (mod+x%mod)%mod

ans = 0
MOD = 10**9 + 7

factorial = 1
for i in range(2,n):
    factorial = (factorial * i%MOD) %MOD

p = [0]*(n-1)
p[0] = 1 * factorial%MOD

for i in range(1,n-1):
    p[i] = p[i-1] + factorial*mod_inv(i+1,MOD)
    p[i] %= MOD

for i in range(n-1):
    ans += (x[i+1]-x[i])%MOD*p[i]
    ans %= MOD

print(int(ans))