using System;
public class Program
{
public static int GetMaxChars(string str) {
int size = str.Length;
int maxCh = 0;
for (int i = 0; i < size - 1; i++) {
for (int j = i + 1; j < size; j++) {
if (str[i] == str[j]) {
int temp = Math.Abs(j - i - 1);
maxCh = maxCh > temp ? maxCh : temp;
}
}
}
return maxCh;
}
public static void Main(string[] args)
{
string str = "aBcaaBdefBgh";
Console.Write(GetMaxChars(str));
}
}
/*
run:
7
*/