a,b,c = map(int,input().split())
n = a+b+c
mod = 10**9+7

### for bigger prime 
N = n+5
fact = [1]*N
finv = [1]*N
 
for i in range(2,N):
    fact[i] = (fact[i-1]*i)%mod
finv[-1] = pow(fact[-1],mod-2,mod)
for i in range(1,N)[::-1]:
    finv[i-1] = (finv[i]*i)%mod

def nCr(n,r):
    if r > n or r < 0:
        return 0
    else: 
        return fact[n]*finv[r]%mod*finv[n-r]%mod

ans = 0
two = pow(2,c-1,mod)
for i in range(c,n):
    cleft = i-1
    numc = nCr(cleft,c-1)
    numb = nCr(n-1-c,b)
    if i-c >= b:
        numb -= nCr(i-c,b)
        numb %= mod
    base = numc*numb
    ans += two*numc*numb%mod
    each = nCr(cleft-1,c-2)
    # print(i,numb,numc,each)
    ans += (two-1)*numb%mod*each%mod
    ans %= mod
    two = (two*2)%mod
# ans *= pow(2,mod-2,mod)
ans %= mod
print(ans)