#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
    int i,j,n,a[100],b[2][100],max=0;
    
    cin >> n;
    
    for(i=0;i<n;i++)
    { cin>>a[i];
     
      b[0][i]=0;b[1][i]=0 ;   
    
      for(j=0;j<=i;j++)
      {  if(a[i]-a[j]==1 || a[i]-a[j]==0 )
         {b[0][i]++;    
          if(b[0][i]>max)
          max=b[0][i];    
          }
       
         if(a[i]-a[j]==-1 || a[i]-a[j]==0 )
         {b[1][i]++;    
          if(b[1][i]>max)
          max=b[1][i];    
         }
      }
 
    } 
    if(max>1) cout<<max;
    else      cout<<max;
        
    return 0;
}