Buggy python submission (verdict: Time Limit Exceeded):
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*10**6+5
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)

Fixed submission:
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*10**6+5
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)

Buggy python submission (verdict: Time Limit Exceeded):
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 10**7
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)

Fixed submission:
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*10**6+5
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)

Buggy python submission (verdict: Runtime Error):
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 10**6
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)


Fixed submission:
r1, c1, r2, c2 = map(int, input().split())
mod = 10**9+7

def cmb1(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod

mod = 10**9+7 #出力の制限
N = 2*10**6+5
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

ans = cmb1(r2+1+c2+1, r2+1, mod)-cmb1(r2+1+c1, c1, mod)-cmb1(r1+c2+1, r1, mod)+cmb1(r1+c1, c1, mod)
print(ans%mod)