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

int main() {
    string s; cin >> s;
    int ss = (int)s.size();
    int ans = 0;
    for (int i = 0; i < ss-2; i++) {
        if (s[i] == s[i+1] || s[i+1] == s[i+2]) ans++;
    }
    cout << ans << endl;
}