#include <iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<stdlib.h>

 #include<vector>

 using namespace std;

 #define N 200010

 int p[N],dp[N][];

 int main()

 {

     int i,a,b;

     scanf("%d%d",&a,&b);

     for(i =  ; i <= b-a+ ; i++)

     scanf("%d",&p[i]);

     dp[][] = ;

     dp[][] = ;

     for(i = ; i <= b-a+ ; i++)

     {

         if(p[i]>p[i-])

         {

             dp[i][] = min(dp[i-][]+,dp[i-][]);

             dp[i][] = min(dp[i-][]+,dp[i-][]+);

         }

         else if(p[i]<p[i-])

         {

             dp[i][] = min(dp[i-][]+,dp[i-][]+);

             dp[i][] = min(dp[i-][]+,dp[i-][]);

         }

         else

         {

             dp[i][] = min(dp[i-][],dp[i-][]+);

             dp[i][] = min(dp[i-][],dp[i-][]+);

         }

     }

     int ans = min(dp[b-a+][],dp[b-a+][]);

     printf("%d\n",ans);

     return ;

 }