#include <bits/stdc++.h>

using namespace std;
const int MOD = 1000000007;
typedef long long LL;
/*
3 5 4

36
*/
int main() {
    LL n, m, k;
    cin >> n >> m >> k;
    // k=4 m=5
    LL a = ((k - 1) * (m - k + 1)) % MOD;

    // LL b = 0;
    // for (LL i = 1; i <= n; i++) b = (b + i) % MOD;
    LL b = (n * (n + 1) / 2) % MOD;

    cout << (a * b) % MOD << endl;
    return 0;
}