#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    std::string s, t;
    std::cin >> s;
    int sz = s.size();

    int ans = 0;
    for (int i = 0; i < sz - 2; i++) {
        t = s.substr(i, 3);
        // std::cout << t << '\n';
        if ((t[0] == t[1] && t[2] != t[1]) || (t[1] == t[2] && t[0] != t[1])) ans++;
    }
    std::cout << ans << '\n';

    return 0;
}