#include <bits/stdc++.h>
using namespace std;
using ll = long long;

// 長さnの順列のうち、辞書順でm番目(0-indexed)の順列(0-indexed)を返す.
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
vector<int> permutation(const int &n, const long long &m) {
    vector<int> r(n);
    long long d = m;
    for (int i = 0; i < n; ++i) {
        r[n - i - 1] = d % (i + 1);
        d /= i + 1;
    }
    __gnu_pbds::tree<int, __gnu_pbds::null_type, less<int>,
                     __gnu_pbds::rb_tree_tag,
                     __gnu_pbds::tree_order_statistics_node_update>
        s;
    for (int i = 0; i < n; ++i) s.insert(i);
    vector<int> p(n);
    for (int i = 0; i < n; ++i) {
        p[i] = *s.find_by_order(r[i]);
        s.erase(p[i]);
    }
    return p;
}

// 受け取った順列(0-indexed)の辞書順での順列番号(0-indexed)を返す.
#include <atcoder/fenwicktree>
template <typename T>
T permorder(const vector<int> &p) {
    int n = p.size();
    vector<T> f(n + 1, 1);
    for (int i = 1; i <= n; ++i) f[i] = f[i - 1] * i;
    atcoder::fenwick_tree<int> bit(n);
    T res = 0;
    for (int i = 0; i < n; ++i) {
        res += (p[i] - bit.sum(0, p[i])) * f[n - i - 1];
        bit.add(p[i], 1);
    }
    return res;
}

// https://yukicoder.me/problems/no/1311
int main() {
    ll n;
    int s;
    cin >> n >> s;
    vector<int> p = permutation(s, n);
    vector<int> pinv(s);
    for (int i = 0; i < s; ++i) pinv[p[i]] = i;
    cout << permorder<ll>(pinv) << endl;
}