#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 510000;
const long long INF = 1LL << 60;
const long long MOD = 1000000007LL;

using namespace std;
typedef unsigned long long ull;
typedef  long long ll;

long long fac[MAX], finv[MAX], inv[MAX];

ll power(ll x, ll n, ll p = 1000000007) {
	if (n == 0) {
		return 1;
	}
	if (n % 2 == 0) {
		return power(x * x % p, n / 2, p) % p;
	}
	else {
		return x * power(x, n - 1, p) % p;
	}
}

void COMinit() {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for (int i = 2; i < MAX; i++) {
		fac[i] = fac[i - 1] * i % MOD;
		inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
		finv[i] = finv[i - 1] * inv[i] % MOD;
	}
}

ll COM(int n, int k) {
	if (n < k) return 0;
	if (n < 0 || k < 0) return 0;
	return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

int main()
{
	COMinit();
	ll a, b, c;
	scanf("%lld %lld %lld", &a, &b, &c);
	ll res = 0;
	ll N = a + b + c;
	for (ll i = 1; i <= a; i++) {
		res += COM(N - i - 2, c - 1) * COM(N - i - c - 1, b - 1) % MOD * (((power(2, N - i - 1, MOD) - 1) % MOD + MOD) % MOD) % MOD;
		res %= MOD;
	}

	printf("%lld\n", res);
	return 0;
}