#include<bits/stdc++.h>

using namespace std;

typedef long long LL;

typedef pair<int, LL>P;

const int M = 2e3 + ;

const LL mod = ;

const LL lINF = 0x3f3f3f3f3f3f3f3f;

#define ls (rt<<1)

#define rs (rt<<1|1)

LL gcd(LL a, LL b) { return b ? gcd(b, a%b) : a; }

string ss;

int flag;

int cnt;

int main()

{

    cin >> ss;

    flag = ;

    while (flag)

    {

        flag = ;

        for (int i = ; i < ss.size(); i++)

        {

            if (i < )

                continue;

            if (ss[i - ] == ss[i - ] && ss[i] == ss[i - ])

            {

                ss.erase(i - , );

                flag = ;

                i -= ;

                cnt++;

            }

        }

    }

    printf("%d\n", cnt);

}