#define ONLINE_JUDGE
#include<bits/stdc++.h>

#define HEAP priority_queue
#define rep(i, n) for(int i = 0, _end_ = (n); i < _end_; ++i)
#define per(i, n) for(int i = (n) - 1; i >= 0 ; --i)
#define forn(i, l, r) for(int i = (l), _end_ = (r); i <= _end_; ++i)
#define nrof(i, r, l) for(int i = (r), _end_ = (l); i >= _end_; --i)
#define FOR(a, b) for(auto (a): (b))
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define X first
#define Y second
#define eps 1e-6
#define pi 3.1415926535897932384626433832795
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(), x.end()
#define FILL(a, b) memset((a), (b), sizeof((a)))
#define MCPY(a, b) memcpy((a), (b), sizeof((b)))

using namespace std;

typedef long long LL;
typedef double flt;
typedef vector<int> vi;
typedef vector<LL> vl;
typedef pair<int,int> pii;
typedef pair<int,LL> pil;
typedef pair<LL,int> pli;
typedef pair<LL,LL> pll;
typedef vector<pil> vil;
typedef vector<pii> vii;
typedef vector<pli> vli;
typedef vector<pll> vll;

const int iinf = 1e9 + 7;
const int oo = 0x3f3f3f3f;
const LL linf = 1ll << 60;
const flt dinf = 1e60;

template <typename T>
inline void scf(T &x)
{
	bool f = 0; x = 0; char c = getchar();
	while((c < '0' || c > '9') && c != '-') c = getchar();
	if(c == '-') { f = 1; c = getchar(); }
	while(c >= '0' && c <= '9') { x = x * 10 + c - '0'; c = getchar(); }
	if(f) x = -x; return;
}
template <typename T1, typename T2>
void scf(T1 &x, T2 &y) { scf(x); return scf(y); }
template <typename T1, typename T2, typename T3>
void scf(T1 &x, T2 &y, T3 &z) { scf(x); scf(y); return scf(z); }
template <typename T1, typename T2, typename T3, typename T4>
void scf(T1 &x, T2 &y, T3 &z, T4 &w) { scf(x); scf(y); scf(z); return scf(w); }

inline char mygetchar(){ char c = getchar(); while(c == ' ' || c == '\n') c = getchar(); return c; }

template <typename T> inline bool chkmax(T &x, const T &y){ return y > x ? x = y, 1 : 0; }
template <typename T> inline bool chkmin(T &x, const T &y){ return y < x ? x = y, 1 : 0; }

#ifdef ONLINE_JUDGE
#define debug(...) ;
#else
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define DEBUG
#endif

//---------------------------------------------------------head----------------------------------------------------

const int maxn = 2e5 + 100;

int n, m, l1, l2;
LL a[maxn], ans, cst[maxn];
pii typ1[maxn], typ2[maxn];
vi in[maxn], out[maxn];

int main()
{
	scf(n, m);
	forn(i, 1, n)
	{
		scf(a[i]);
		if(i == 1) continue;
		if(a[i - 1] != a[i])
		{
			if(a[i - 1] < a[i])
			{
				ans += 1ll * (a[i] - a[i - 1]);
				typ1[l1++] = mp(a[i - 1], a[i]);
			}
			else
			{
				ans += 1ll * (a[i] + m - a[i - 1]);
				typ2[l2++] = mp(a[i - 1], a[i] + m);
			}
		}
	}
	rep(i, l1) if(typ1[i].X != typ1[i].Y) in[typ1[i].X].pb(i), out[typ1[i].Y].pb(i);
	LL cur = 0; int cnt = 0;
	forn(i, 1, m)
	{
		cst[i] += cur + 1ll * cnt * (i - 1);
		for(int j: out[i]) cur += 1ll * typ1[j].X, --cnt;
		for(int j: in[i]) cur -= 1ll * typ1[j].X, ++cnt;
	}
	cur = 0; cnt = 0;
	forn(i, 1, m * 2) in[i].clear(), out[i].clear();
	rep(i, l2) if(typ2[i].X != typ2[i].Y) in[typ2[i].X].pb(i), out[typ2[i].Y].pb(i);
	forn(i, 1, 2 * m)
	{
		cst[i > m ? i - m : i] += cur + 1ll * cnt * (i - 1);
		for(int j: out[i]) cur += 1ll * typ2[j].X, --cnt;
		for(int j: in[i]) cur -= 1ll * typ2[j].X, ++cnt;
	}
	LL mx = -linf;
	forn(i, 1, m) chkmax(mx, cst[i]);
	ans -= mx;
	printf("%lld\n", ans);
	return 0;
}

Measured memory_bytes: 19840