#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vs = vector<string>;
using vpi = vector<pair<int, int>>;
using vpl = vector<pair<ll, ll>>;
#define rep(i, s, n) for (int i = (s); i < (int)(n); ++i)
#define repr(i, s, n) for (int i = (s); i >= (int)(n); --i)
#define sz(x) ((int)(x).size())
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
auto _ = []{ios::sync_with_stdio(false); cin.tie(nullptr); return 0;}();
const int INFI = 1 << 30;
const ll INFL = 1LL << 62;

int main() {
	string s;
	cin >> s;
	int n=sz(s);
	ll sm=0;

	rep (i, 0, n-2){
		map<char,int>mp;
		rep (j, 0, 3){
			mp[s[i+j]]++;
		}
		if(sz(mp)!=2)continue;
		sm++;
	}
	cout << sm << '\n';
	
	return 0;
}