gistfile1.txt

import Foundation

// Enter your code here 

// Enter your code here 

let response = readLine()

//print(response)

var arr = readLine()!.characters.map { String($0) }
var arr2 = [String]()
var prviuse = ""
var filterDate = ""
var isDone = true
while isDone {
    isDone = false
    for i in 0..<arr.count {
        if prviuse == arr[i]{
			for  j in 0..<arr.count {
				if  prviuse == arr[j]{
					
					arr[j] = ""
					
				}
				
			}
            
            prviuse = ""
            isDone = true
        }else{
            prviuse = arr[i]
        }
    }
    arr2 = []
    for item in arr {
        if item != "" {
            arr2.append(item)        }
    }
    prviuse = ""
    arr = arr2
    
}

//print(arr)

var chars = [String]()
var numberOfChars = [Int]()

var counter = 0
for item in 0..<arr.count{
    var found = false
    //print(item)
    if chars.count<1{
      chars.append(arr[item])
      numberOfChars.append(1)
    }else{
        for char in 0..<chars.count{
            if chars[char] == arr[item] {
              found =  true
				numberOfChars[char] = numberOfChars[char] + 1 
            }
        }
        
        if !found {
		   chars.append(arr[item])
           numberOfChars.append(1)
        }
    }
}

//print(chars)

//print(numberOfChars)

 var previuse  = 0

if numberOfChars.count > 0 {
  for i in  1..<numberOfChars.count {
	
	if (numberOfChars[i-1] ==  numberOfChars [i] || numberOfChars[i-1] ==     numberOfChars [i] + 1)  || (numberOfChars[i-1] ==  numberOfChars [i] - 1)    {
		let total = numberOfChars[i-1] + numberOfChars [i]
		if previuse <  total{
			
			previuse = total
		}
	}
	
  }
}

print(previuse)