/*

 ID: cuizhe

 LANG: C++

 TASK: hidden

 */

 #include <cstdio>

 #include <cstring>

 #include <string>

 #include <cmath>

 #include <algorithm>

 using namespace std;

 int que1[],que2[];

 char str[];

 int main()

 {

     int i,len,minz,num,tnum,temp;

     char ch;

     freopen("hidden.in","r",stdin);

     freopen("hidden.out","w",stdout);

     scanf("%d",&len);

     for(i = ;i < len;)

     {

         scanf("%c",&ch);

         if(ch != '\n')

         str[i++] = ch;

     }

     for(i = len;i < *len;i ++)

     {

         str[i] = str[i-len];

     }

     minz = ;

     num = ;

     for(i = ;i < len;i ++)

     {

         if(minz > str[i]-'a')

         {

             num = ;

             minz = str[i]-'a';

             que1[num++] = i;

         }

         else if(minz == str[i]-'a')

         {

             if(i != &&str[i-]-'a' == minz)

             continue;//优化1

             que1[num++] = i;

         }

     }

     for(temp = ;;temp ++)

     {

         if(num == ) break;

         minz = ;

         for(i = ;i < num;i ++)

         {

             if(minz > str[que1[i]+]-'a')

             {

                 minz = str[que1[i]+]-'a';

                 tnum = ;

                 que2[tnum++] = que1[i]+;

             }

             else if(minz == str[que1[i]+]-'a')

             {

                  if(que2[tnum-] >= que1[i]+ -temp)

                  continue;//优化2

                  que2[tnum++] = que1[i]+;

             }

         }

         for(i = ;i < tnum;i ++)

         que1[i] = que2[i];

         num = tnum;

     }

     printf("%d\n",que1[]-temp);

     return ;

 }