a, b, c = map(int, input().split())
N = a + b + c
MOD = 10 ** 9 + 7
MAX = 3 * 10 ** 5 + 10
# https://tjkendev.github.io/procon-library/python/math/factorial.html から拝借しています。
fact = [1] * (MAX + 1)
rfact = [1] * (MAX + 1)
r = 1
for i in range(1, MAX + 1):
    fact[i] = r = r * i % MOD
rfact[MAX] = r = pow(fact[MAX], MOD - 2, MOD)
for i in range(MAX, 0, -1):
    rfact[i - 1] = r = r * i % MOD


def comb(n, k, error=0):
    if not 0 <= k <= n:
        return error
    return fact[n] * rfact[k] * rfact[n - k] % MOD


ans = 0
p2 = 1
for i in range(N - 2):
    ct = (comb(a + b - 1, b) - comb(i + 1 - c, b)) % MOD
    val_sum = comb(i, c - 1) * p2 % MOD
    if i >= 1:
        val_sum += comb(i - 1, c - 2) * (p2 - 1) % MOD
    p2 *= 2
    p2 %= MOD
    ans += ct * val_sum
    ans %= MOD
print(ans)