#define _DEBUG 0
#if _DEBUG
#endif

#include<stdio.h>
#include<stdbool.h>
#include<string.h>
#include<stdlib.h>
int main(void)
{
  int scan;//scanf警告用
  int ans=0;
  int i, j;
  
  char s[200010];
  scan=scanf("%s",s);
  int slen=strlen(s);
  for(i=2; i<slen; i++)
  {
    int count[256]={0};
    count[s[i-2]]++;
    count[s[i-1]]++;
    count[s[i-0]]++;
    bool ok=true;
    for(j=0;j<256;j++)
    {
      if(3<=count[j]){ok=false;break;}
    }
    if(!(s[i-2]==s[i-1] || s[i-1]==s[i-0]))ok=false;
    if(ok)ans++;
  }
  printf("%d", ans);
  return scan-scan;
}