LCD

#define task "LCD"

#include <iostream>
#include <cstdio>

using namespace std;

using ll = long long;
using ld = long double;

constexpr int N = 1e6 + 5;
constexpr ll Inf = 1e17;
int n, m;
int a[N];
ll b[N * 2];

void Read()
{
    cin >> n >> m;
    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i];
        --a[i]; /// Change 1, 2, ..., m -> 0, 1, 2, ..., (m - 1)
    }
}

void Solve()
{
    ll sum(0); // Answer without X

    for (int i = 1; i < n; ++i)
    {
        if (a[i] > a[i + 1])
            a[i + 1] += m;

        sum += a[i + 1] - a[i];

        b[a[i] + 2] += 1;
        b[a[i + 1] + 1] += -1 - (a[i + 1] - a[i] - 1);
        b[a[i + 1] + 2] += (a[i + 1] - a[i] - 1);

        if (a[i + 1] >= m)
            a[i + 1] -= m;
    }

    for (int i = 1; i < m * 2; ++i)
        b[i] += b[i - 1];

    for (int i = 1; i < m * 2; ++i)
        b[i] += b[i - 1];

    ll ans(Inf);

    for (int i = 0; i < m; ++i)
        ans = min(ans, sum - b[i] - b[i + m]);

    cout << ans;
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }
    Read();
    Solve();
}

/*
4 5
1 2 4 5
*/