#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    string sub = s;
    int count = 0;
    for(int i = 0; i < s.size()-2; i++){
        int x = 0;
        if(sub.at(i) == sub.at(i+1)){
            x++;
        }
        if(sub.at(i+1) == sub.at(i+2)){
            x++;
        }
        if(sub.at(i+2) == sub.at(i+0)){
            x++;
        }
        if(x == 1){
            count++;
        }
    }

    cout << count;

    return 0;
}