a,b,c = map(int,input().split())
N = a + b + c
X = [0] * N

MOD = 10 ** 9 + 7
fact = [1]*(N+1)
rfact = [1]*(N+1)
r = 1
for i in range(1, N+1):
    fact[i] = r = r * i % MOD
rfact[N] = r = pow(fact[N], -1, MOD)
for i in range(N, 0, -1):
    rfact[i-1] = r = r * i % MOD

def comb(n, k):
    return fact[n] * rfact[k] * rfact[n-k] % MOD

ans = 0
b2 = b - 1
c2 = c - 1
now = 0
for i in range(N - 2):
    if i < a:
        a2 = a - i - 1
        now += (fact[a2+b2+c2] * rfact[a2] * rfact[b2] * rfact[c2]) % MOD
    X[N - i - 3] = now
ans = 0
for i in range(N):
    ans += X[i] * pow(2,i,MOD)
    ans %= MOD
print(ans)