Buggy python submission (verdict: Runtime Error):
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Fixed submission:
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6+10
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Buggy python submission (verdict: Time Limit Exceeded):
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Fixed submission:
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6+10
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Buggy python submission (verdict: Time Limit Exceeded):
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=10**7
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Fixed submission:
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6+10
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Buggy python submission (verdict: Time Limit Exceeded):
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=10**7
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Fixed submission:
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6+10
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Buggy python submission (verdict: Runtime Error):
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=10**6
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)

Fixed submission:
r1,c1,r2,c2=map(int,input().split())

def cmb(n, r, p):
    if (r < 0) or (n < r):
        return 0
    r = min(r, n - r)
    return fact[n] * factinv[r] * factinv[n-r] % p

p=10**9+7
N=2*10**6+10
fact = [1, 1]
factinv = [1, 1]
inv = [0, 1]
 
for i in range(2, N + 1):
    fact.append((fact[-1] * i) % p)
    inv.append((-inv[p % i] * (p // i)) % p)
    factinv.append((factinv[-1] * inv[-1]) % p)

print((cmb(r2+1+c2+1,c2+1,p)-cmb(r1+c2+1,c2+1,p)-cmb(r2+1+c1,c1,p)+cmb(r1+c1,c1,p))%p)