import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;


public class Main {
  public static void main(String[] args) {
    FastScanner sc = new FastScanner();
    int n = sc.nextInt();
    int m = sc.nextInt();
    int[] a = sc.nextIntList(n);

    
    long[][] imos = new long[2][m + 2];
    
    for (int i = 0; i < n - 1; i ++) {
      if (a[i] < a[i + 1]) {
        // x <= a[i] or x > a[i + 1] : a[i + 1] - a[i]
        // a[i] < x <= a[i + 1] : 1 + a[i + 1] - x
        
        long d1 = a[i + 1] - a[i];
        imos[0][1] += d1;
        imos[0][a[i] + 1] -=d1;
        imos[0][a[i + 1] + 1] += d1;
        imos[0][m + 1] -= d1;
        
        long e1 = 1 + a[i + 1];
        long e2 = -1;
        imos[0][a[i] + 1] += e1;
        imos[1][a[i] + 1] += e2;
        imos[0][a[i + 1] + 1] -= e1;
        imos[1][a[i + 1] + 1] -= e2;
      } else {
        // x <= a[i + 1] : 1 + a[i + 1] - x
        // a[i + 1] < x <= a[i] : m - a[i] + a[i + 1]
        // x > a[i] : 1 + m - x + a[i + 1]
        
        int d1 = 1 + a[i + 1];
        int d2 = -1;
        
        int e1 = m - a[i] + a[i + 1];
        
        int f1 = 1 + m + a[i + 1];
        int f2 = -1;
        
        imos[0][1] += d1;
        imos[0][a[i + 1] + 1] -= d1;
        imos[1][1] += d2;
        imos[1][a[i + 1] + 1] -= d2;
        
        imos[0][a[i + 1] + 1] += e1;
        imos[0][a[i] + 1] -= e1;
        
        imos[0][a[i] + 1] += f1;
        imos[0][m + 1] -= f1;
        imos[1][a[i] + 1] += f2;
        imos[1][m + 1] -= f2;
      }
    }
    
    long[][] sum = new long[2][m + 2];
    for (int i = 1; i < m + 2; i ++) {
      for (int j = 0; j < 2; j ++) {
        sum[j][i] += sum[j][i - 1] + imos[j][i];
      }
    }
    
    long ret = Long.MAX_VALUE;
    for (int i = 1; i <= m; i ++) {
      ret = Math.min(ret, sum[0][i] + sum[1][i] * i);
    }
    System.out.println(ret);
  }
  


}


class FastScanner {
	public static String debug = null;

	private final InputStream in = System.in;
	private int ptr = 0;
	private int buflen = 0;
	private byte[] buffer = new byte[1024];
	private boolean eos = false;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				if (debug != null) {
					buflen = debug.length();
					buffer = debug.getBytes();
					debug = "";
					eos = true;
				} else {
					buflen = in.read(buffer);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen < 0) {
				eos = true;
				return false;
			} else if (buflen == 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	private void skipUnprintable() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
	}

	public boolean isEOS() {
		return this.eos;
	}

	public boolean hasNext() {
		skipUnprintable();
		return hasNextByte();
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		return (int) nextLong();
	}

	public long[] nextLongList(int n) {
		return nextLongTable(1, n)[0];
	}

	public int[] nextIntList(int n) {
		return nextIntTable(1, n)[0];
	}

	public long[][] nextLongTable(int n, int m) {
		long[][] ret = new long[n][m];
		for (int i = 0; i < n; i ++) {
			for (int j = 0; j < m; j ++) {
				ret[i][j] = nextLong();
			}
		}
		return ret;
	}

	public int[][] nextIntTable(int n, int m) {
		int[][] ret = new int[n][m];
		for (int i = 0; i < n; i ++) {
			for (int j = 0; j < m; j ++) {
				ret[i][j] = nextInt();
			}
		}
		return ret;
	}
}

Measured memory_bytes: 26816