Codeforces Round #256 (Div. 2)——Multiplication Table

LL n, m, k;

LL fun(LL goal)
{
    LL t = 0, ret = 0;
    while (++t <= m)
    {
        ret += min(n, goal / t);
    }
    return ret;
}

LL bin(LL L, LL R, LL goal)
{
    LL M, V;
    while (L <= R)
    {
        M = (L + R) >> 1;
        V = fun(M);
        if (V < goal)
            L = M + 1;
        else
            R = M - 1;
    }
    return L;
}

int main()
{
//    freopen("in.txt", "r", stdin);
    while (cin >> n >> m >> k)
    {
        cout << bin(1, 1e15, k) << endl;
    }
    return 0;
}