#include <cstdio>

const int md = 1000000007;

inline int add(int a, int b) 
{
	a += b;
	if (a >= md) a -= md;
	return a;
}
inline int sub(int a, int b) 
{
	a -= b;
	if (a < 0) a += md;
	return a;
}
inline int mul(int a, int b) 
{
	return (long long)a * b % md;
}
inline int po(int a, int b) 
{
	int r = 1;
	while (b) {
		if (b & 1) r = mul(r, a);
		a = mul(a, a);
		b >>= 1;
	}
	return r;
}
inline int inv(int a) 
{
	return po(a, md - 2);
}

const int N = 1000000;
int fact[2 * N + 1];

inline int nCr(int n, int r) 
{
	if (r < 0) return 0;
	return mul(fact[n], inv(mul(fact[r], fact[n - r])));
}

int n, m, k;

int main() 
{
	fact[0] = 1;
	for (int i = 1; i <= 2 * N; ++i) fact[i] = mul(fact[i - 1], i);
	scanf("%d%d%d", &n, &m, &k);
	if (n > m + k) printf("0\n");
	else printf("%d\n", sub(nCr(n + m, n), nCr(n + m, n - k - 1)));
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
/* * * *   * * *   	* * * */
#define mp make_pair
typedef long long ll;
typedef pair<int, int> pii;
/* * * *   * * *   	* * * */
/* *
 *
 * Too many mind, no mind.
 *
 * */
const int mod = 3;
int add(int a, int b) { return a + b >= mod ? a + b - mod : a + b; }
int sub(int a, int b) { return a >= b ? a - b : a - b + mod; }
int mul(int a, int b) { return a * b % mod; }
int pasc[3][3];
int choose(int n, int k) {//Luca's Theorem
	if (k < 0 || k > n) return 0;
	int ans = 1;
	while (n) {
		int x = n % mod, y = k % mod;
		n /= mod, k /= mod;
		ans = mul(pasc[x][y], ans);
	}
	return ans;
}
int main(){
	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	pasc[0][0] = 1;
	for (int i = 1; i < 3; ++i) {
		pasc[i][0] = pasc[i][i] = 1;
		for (int j = 1; j < 3; ++j) pasc[i][j] = add(pasc[i - 1][j], pasc[i - 1][j - 1]);
	}
	int n; cin >> n;
	string s; cin >> s;
	int ans = 0;
	for (int i = 0; i < n; ++i) {
		int ai;
		if (s[i] == 'B') ai = 0;
		else if (s[i] == 'W') ai = 1;
		else ai = 2;
		ans = add(ans, mul(ai, choose(n - 1, i)));//Binomial coefficient
	}
	if (!(n & 1)) ans = (-ans + 6) % mod;
	/*
	for (int i = 0; i < n - 1; ++i) {
		if (ans & 1) ans += 3;
		ans /= 2;
	}
	*/
	if (ans == 0) cout << 'B';
	else if (ans == 1) cout << 'W';
	else cout << 'R';
	cout << '\n';
	return 0;
}
