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

// template {{{
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define lb lower_bound
#define ub upper_bound
#define f first
#define s second
#define resz resize

#define sz(x) int((x).size())
#define all(x) (x).begin(), (x).end()

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)

#define sort_by(x, y) sort(all(x), [&](const auto& a, const auto& b) { return y; })

using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vb = vector<bool>;
using vd = vector<double>;
using vs = vector<string>;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<double, double>;

using vpii = vector<pii>;
using vpll = vector<pll>;
using vpdd = vector<pdd>;

template<typename T> void ckmin(T& a, const T& b) { a = min(a, b); }
template<typename T> void ckmax(T& a, const T& b) { a = max(a, b); }

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

namespace __input {
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
        re(first); re(rest...);
    }

    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.f,p.s); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
}
using namespace __input;

namespace __output {
    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
        pr(first); pr(rest...);
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) {
        pr("{",x.f,", ",x.s,"}");
    }
    template<class T, bool pretty = true> void prContain(const T& x) {
        if (pretty) pr("{");
        bool fst = 1; for (const auto& a: x) pr(!fst?pretty?", ":" ":"",a), fst = 0;
        if (pretty) pr("}");
    }
    template<class T> void pc(const T& x) { prContain<T, false>(x); pr("\n"); }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }

    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) {
        pr(first); ps();
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
        pr(first," "); ps(rest...);
    }
}
using namespace __output;

#define TRACE(x) x
#define __pn(x) pr(#x, " = ")
#define pd(...) __pn((__VA_ARGS__)), ps(__VA_ARGS__), cout << flush

namespace __algorithm {
    template<typename T> void dedup(vector<T>& v) {
        sort(all(v)); v.erase(unique(all(v)), v.end());
    }
    template<typename T> typename vector<T>::iterator find(const vector<T>& v, const T& x) {
        auto it = lower_bound(all(v), x); return it != v.end() && *it == x ? it : v.end();
    }
    template<typename T> size_t index(const vector<T>& v, const T& x) {
        auto it = find(v, x); assert(it != v.end() && *it == x); return it - v.begin();
    }

    template<typename T1, typename T2> typename vector<pair<T1, T2>>::iterator lower_bound(
            const vector<pair<T1, T2>>& v, const T1& x) {
        return lower_bound(all(v), x, [](pair<T1, T2> a, pair<T1, T2> b) { return a.f < b.f; });
    }
    template<typename T1, typename T2> typename vector<pair<T1, T2>>::iterator upper_bound(
            const vector<pair<T1, T2>>& v, const T1& x) {
        return upper_bound(all(v), x, [](pair<T1, T2> a, pair<T1, T2> b) { return a.f < b.f; });
    }
}
using namespace __algorithm;

struct monostate {
    friend istream& operator>>(istream& is, const __attribute__((unused))monostate& ms) { return is; }
    friend ostream& operator<<(ostream& os, const __attribute__((unused))monostate& ms) { return os; }
} ms;

template<typename W=monostate> struct wedge {
    int u, v, i; W w;
    wedge<W>(int _u=-1, int _v=-1, int _i=-1) : u(_u), v(_v), i(_i) {}
    int operator[](int loc) const { return u ^ v ^ loc; }
    friend void re(wedge& e) { re(e.u, e.v, e.w); --e.u, --e.v; }
    friend void pr(const wedge& e) { pr(e.u, "<-", e.w, "->", e.v); }
};

namespace __io {
    void setIn(string s) { freopen(s.c_str(),"r",stdin); }
    void setOut(string s) { freopen(s.c_str(),"w",stdout); }
    void setIO(string s = "") {
        ios_base::sync_with_stdio(0); cin.tie(0);
        if (sz(s)) { setIn(s+".in"), setOut(s+".out"); }
    }
}
using namespace __io;
// }}}

// binary_indexed_tree {{{
template<typename T> struct binary_indexed_tree {
    int S;
    vector<T> table;

    binary_indexed_tree<T>(int _S = 0) : S(_S) {
        table.resize(S+1);
    }

    // Adds v to the element at index i
    void add(int i, T v) {
        for (i++; i <= S; i += i&-i)
            table[i] = table[i] + v;
    }

    // Replaces the element at index i with v
    void replace(int i, T v) {
        add(i, v - sum(i, i+1));
    }

    // Returns the sum of the elements at indices in [0, i)
    T sum(int i) const {
        T res{};
        for (; i; i -= i&-i)
            res = res + table[i];
        return res;
    }

    // Returns the sum of the elements at indices in [l, r)
    T sum(int l, int r) const {
        return l > r ? T{} : sum(r) - sum(l);
    }

    /*
     * Returns the first i in [0, S] such that comp(sum(i)) is true.
     * Returns -1 if no such i exists.
     * Requires that comp(sum(i)) is non-decreasing in i.
     * The empty prefix is considered to have sum equal to T().
     */
    int lower_bound(const auto& comp) const {
        T cur = T{};
        if (comp(cur)) return 0;

        int inx = 0;
        for (int i = 31 - __builtin_clz(S); i >= 0; i--) {
            int nxt = inx + (1 << i);
            if (nxt <= S && !comp(cur + table[nxt])) {
                inx = nxt;
                cur = cur + table[nxt];
            }
        }

        return inx < S ? inx + 1 : -1;
    }
};
// }}}

int main() {
    setIO();

    int N, M; re(N, M); vi a(N); re(a); trav(e, a) --e;

    vpii ch;
    ll ans = 0;

    F0R (i, N - 1) {
        assert(a[i] != a[i+1]);
        ch.eb(a[i] < a[i+1] ? a[i] + M : a[i], a[i+1] + M);
        ans += ch.back().s - ch.back().f;
    }

    sort_by(ch, a.s < b.s);
    F0R (i, N - 1) {
        ch.eb(ch[i].f + M, ch[i].s + M);
    }

    ll save = 0;
    binary_indexed_tree<int> live(3 * M);
    binary_indexed_tree<ll> ssum(3 * M);

    F0Rd (b, sz(ch)) {
        live.add(ch[b].f, 1);
        ssum.add(ch[b].f, ch[b].f);

        if (b + N-1 < sz(ch)) {
            live.add(ch[b+N-1].f, -1);
            ssum.add(ch[b+N-1].f, -ch[b+N-1].f);
        }

        int help = live.sum(ch[b].s);
        ll starts = ssum.sum(ch[b].s);

        ll cand = help * ll(ch[b].s) - help - starts;

        ckmax(save, cand);
    }

    ps(ans - save);

    return 0;
}




Measured memory_bytes: 5872