#!/usr/bin/env python
# coding: utf-8

# In[1]:


n,a,b = map(int, input().split())


# In[2]:


def nCk(n, k, mod):
    a = 1
    for i in range(n, n-k, -1):
        a *= i
        a %= mod
    b = 1
    for i in range(1, k+1):
        b *= i
        b %= mod
    a *= pow(b, mod-2, mod)
    return a


# In[3]:


mod = 10**9+7
ans = pow(2, n, mod)-1
ans -= nCk(n, a, mod) + nCk(n, b, mod)
print(ans%mod)


# In[ ]:



 n,a,b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b def nCk(n, k, mod):
    a = 1
    for i in range(n, n-k, -1):
        a *= i
        a %= mod
    b = 1
    for i in range(1, k+1):
        b *= i
        b %= mod
    a *= pow(b, mod-2, mod)
    return a


# In[3]: nCk a = 1 a 1 for i in range(n, n-k, -1):
        a *= i
        a %= mod
     i range(n, n-k, -1) range n n-k n k -1 a *= i a i a %= mod a mod b = 1 b 1 for i in range(1, k+1):
        b *= i
        b %= mod
     i range(1, k+1) range 1 k+1 k 1 b *= i b i b %= mod b mod a *= pow(b, mod-2, mod) a pow(b, mod-2, mod) pow b mod-2 mod 2 mod return a a n n k k mod mod mod = 10**9+7 mod 10**9+7 10**9 10 9 7 ans = pow(2, n, mod)-1 ans pow(2, n, mod)-1 pow(2, n, mod) pow 2 n mod 1 ans -= nCk(n, a, mod) + nCk(n, b, mod) ans nCk(n, a, mod) + nCk(n, b, mod) nCk(n, a, mod) nCk n a mod nCk(n, b, mod) nCk n b mod print(ans%mod) print ans%mod ans mod b = map(int, input().split()) map(int, input().split()) b a,b = map(int, input().split()) map(int, input().split()) a ans = pow(2, n, mod)-1 pow(2, n, mod)-1 ans mod = 10**9+7 10**9+7 mod ans -= nCk(n, a, mod) + nCk(n, b, mod) nCk(n, a, mod) + nCk(n, b, mod) ans n,a,b = map(int, input().split()) map(int, input().split()) n def nCk(n, k, mod):
    a = 1
    for i in range(n, n-k, -1):
        a *= i
        a %= mod
    b = 1
    for i in range(1, k+1):
        b *= i
        b %= mod
    a *= pow(b, mod-2, mod)
    return a


# In[3]: def nCk(n, k, mod):
    a = 1
    for i in range(n, n-k, -1):
        a *= i
        a %= mod
    b = 1
    for i in range(1, k+1):
        b *= i
        b %= mod
    a *= pow(b, mod-2, mod)
    return a


# In[3]: nCk
#!/usr/bin/env python
# coding: utf-8

# In[1]:


n,a,b = map(int, input().split())


# In[2]:


def nCk(n, k, mod):
    a = 1
    for i in range(n, n-k, -1):
        a *= i
        a %= mod
    b = 1
    for i in range(1, k+1):
        b *= i
        b %= mod
    a *= pow(b, mod-2, mod)
    return a


# In[3]:


mod = 10**9+7
ans = pow(2, n, mod)-1
ans -= nCk(n, a, mod) + nCk(n, b, mod)
print(ans%mod)


# In[ ]:




