#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
#include <cfloat>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <cstring>
#include <assert.h>
#include <sys/time.h>
#include <fstream>

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)  FOR(i,0,n)
#define REP(i,n)  FOR(i,0,n)
#define each(i,c) for(auto i=(c).begin(); i!=(c).end(); ++i)
#define EACH(i,c) for(auto i=(c).begin(); i!=(c).end(); ++i)
#define exist(s,e) ((s).find(e)!=(s).end())

#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
#define deb(x) cerr << #x << " = " << (x) << " , ";
#define debl cerr << " (L" << __LINE__ << ")"<< endl;
#define sz(s) (int)((s).size())


#define clr(a) memset((a),0,sizeof(a))
#define nclr(a) memset((a),-1,sizeof(a))
#define pb push_back
#define INRANGE(x,s,e) ((s)<=(x) && (x)<(e))
#define MP(x,y) make_pair((x),(y))

double pi=3.14159265358979323846;

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<double> vd;
typedef vector<vd> vvd;
typedef vector<string> vs;

template<typename T> std::ostream& operator<<(std::ostream& os, const vector<T>& z){
	os << "[ ";
	REP(i,z.size())os << z[i] << ", " ;
	return ( os << "]" << endl);
}

template<typename T> std::ostream& operator<<(std::ostream& os, const set<T>& z){
	os << "set( ";
	EACH(p,z)os << (*p) << ", " ;
	return ( os << ")" << endl);
}

template<typename T,typename U> std::ostream& operator<<(std::ostream& os, const map<T,U>& z){
	os << "{ ";
	EACH(p,z)os << (p->first) << ": " << (p->second) << ", " ;
	return ( os << "}" << endl);
}

template<typename T,typename U> std::ostream& operator<<(std::ostream& os, const pair<T,U>& z){
	return ( os << "(" << z.first << ", " << z.second << ",)" );
}

double get_time(){
	struct timeval tv;
	gettimeofday(&tv, NULL);
	return tv.tv_sec + tv.tv_usec*1e-6;
}

typedef unsigned int uint32_t;
struct RND{
	uint32_t x;
	uint32_t y;
	uint32_t z;
	uint32_t w;
	RND(){
		x=123456789;
		y=362436069;
		z=521288629;
		w=88675123;
	}
	void init(int seed){
		x=123456789;
		y=362436069;
		z=521288629;
		w=seed+100;
		REP(i,10)get();
	}
	uint32_t get(){
		uint32_t t;
		t=x^(x<<11);
		x=y;y=z;z=w;
		w=(w^(w>>19))^(t^(t>>8));
		return w;
	}
};
RND rnd;

template<typename T>struct fenwick_tree{
	vector<T> x;
	fenwick_tree(int n){
		int m=1;
		while(m<n)m*=2;
		x=vector<T> (m);
	}
	// [i,j)区間
	void range(int i,int j, T d){
		if(i!=0){
			range(0,j,d);
			range(0,i,-d);
			return;
		}
		j-=1;
		for( ;j>=0;j=(j&(j+1))-1){
			x[j]+=d;
		}
	}
	T point(int k){
		T ret=0;
		for(;k<x.size(); k|=k+1) ret+=x[k];
		return ret;
	}
};

void _main(istream &inp){
	ll n,m;
	inp >> n >> m;
	fenwick_tree<ll> ft1(m);
	fenwick_tree<ll> ft0(m);
	vl a(n);
	rep(i,n) inp >> a[i];
	rep(i,n)a[i]-=1;
	ll tot = 0;
	rep(i,n-1){
		ll x = a[i];
		ll y = a[i+1];
		if(x<y){
			tot += y-x;
			ft1.range(x+1, y+1,1);
			ft0.range(x+1, y+1,-x-1);
		}
		else{
			tot += y+m-x;
			ft1.range(x+1,m,1);
			ft0.range(x+1,m,-x-1);
			ft1.range(0,y+1,1);
			ft0.range(0,y+1,m-x-1);
		}
	}
	ll mini = -1;
//	deb(n);deb(m);deb(a);
	rep(i,m){
		ll res = tot - ft1.point(i)*i - ft0.point(i);
		if(mini==-1 || res<mini){
			mini = res;
		}
//		deb(i);deb(res);debl;
	}
	cout << mini << endl;

}

int main(){
	if(0){
		ifstream ifs("test.txt");
		_main(ifs);
	}
	else{
		_main(cin);
	}
	return 0;
}


Measured memory_bytes: 3072