import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Main {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	static void solve()
	{
		int n = ni(), m = ni();
		int[] a = na(n);
		for(int i = 0;i < n;i++){
			a[i]--;
		}
		long ans = 0;
		long[] imos = new long[m+3];
		long[] imos2 = new long[m+3];
		for(int i = 0;i < n-1;i++){
			int x = a[i], y = a[i+1];
			if(x > y){
				y += m;
			}
			ans += y-x;
			if(x+2 <= y){
				int z = x+2;
				if(z >= m){
					z -= m;
					y -= m;
				}
				if(y < m){
					imos2[z]--;
					imos2[y+1]++;
					imos[y+1] += y-z+1;
				}else{
					imos2[z]--;
					imos2[0]--;
					imos2[y-m+1]++;
					imos[0] -= m-z;
					imos[y-m+1] += y-z+1;
				}
			}
		}
		for(int i = 0;i < m;i++){
			imos2[i+1] += imos2[i];
		}
		for(int i = 0;i < m;i++){
			imos[i] += imos2[i];
		}
		for(int i = 0;i < m;i++){
			imos[i+1] += imos[i];
		}
		long ret = 0;
		for(int i = 0;i < m;i++){
//			out.println(imos[i]+ans);
			ret = Math.min(ret, imos[i]);
		}
		out.println(ans+ret);
	}
	
	public static long sumFenwick(long[] ft, int i)
	{
		long sum = 0;
		for(i++;i > 0;i -= i&-i)sum += ft[i];
		return sum;
	}
	
	public static void addFenwick(long[] ft, int i, long v)
	{
		if(v == 0)return;
		int n = ft.length;
		for(i++;i < n;i += i&-i)ft[i] += v;
	}
	
	public static int firstGEFenwick(long[] ft, long v)
	{
		int i = 0, n = ft.length;
		for(int b = Integer.highestOneBit(n);b != 0;b >>= 1){
			if((i|b) < n && ft[i|b] < v){
				i |= b;
				v -= ft[i];
			}
		}
		return i;
	}
	
	public static long[] restoreFenwick(long[] ft)
	{
		int n = ft.length-1;
		long[] ret = new long[n];
		for(int i = 0;i < n;i++)ret[i] = sumFenwick(ft, i);
		for(int i = n-1;i >= 1;i--)ret[i] -= ret[i-1];
		return ret;
	}
	
	public static int findGFenwick(long[] ft, long v)
	{
		int i = 0;
		int n = ft.length;
		for(int b = Integer.highestOneBit(n);b != 0 && i < n;b >>= 1){
			if(i + b < n){
				int t = i + b;
				if(v >= ft[t]){
					i = t;
					v -= ft[t];
				}
			}
		}
		return v != 0 ? -(i+1) : i-1;
	}
	
	public static long[] buildFenwick(long[] a)
	{
		int n = a.length;
		long[] ft = new long[n+1];
		System.arraycopy(a, 0, ft, 1, n);
		for(int k = 2, h = 1;k <= n;k*=2, h*=2){
			for(int i = k;i <= n;i+=k){
				ft[i] += ft[i-h];
			}
		}
		return ft;
	}
	
	public static void addRangeFenwick(long[] ft0, long[] ft1, int i, long v)
	{
		addFenwick(ft1, i+1, -v);
		addFenwick(ft1, 0, v);
		addFenwick(ft0, i+1, v*(i+1));
	}
	
	public static void addRangeFenwick(long[] ft0, long[] ft1, int a, int b, long v)
	{
		if(a <= b){
			addFenwick(ft1, b+1, -v);
			addFenwick(ft0, b+1, v*(b+1));
			addFenwick(ft1, a, v);
			addFenwick(ft0, a, -v*a);
		}
	}
	
	public static long sumRangeFenwick(long[] ft0, long[] ft1, int i)
	{
		return sumFenwick(ft1, i) * (i+1) + sumFenwick(ft0, i);
	}
	
	public static long[] restoreRangeFenwick(long[] ft0, long[] ft1)
	{
		int n = ft0.length-1;
		long[] ret = new long[n];
		for(int i = 0;i < n;i++)ret[i] = sumRangeFenwick(ft0, ft1, i);
		for(int i = n-1;i >= 1;i--)ret[i] -= ret[i-1];
		return ret;
	}

	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
//	private static boolean isSpaceChar(int c) { return !(c >= 32 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private static char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}


Measured memory_bytes: 24020