#include <iostream>
#include <fstream>
#include <vector>
#include <bits/stl_algo.h>

using namespace std;

void changeside(char &c) {
    if (c == 'L')
        c = 'R';
    else
        c = 'L';
}

int howmuchsameletters(char c, vector<char> v) {
    int i = 0;
    for (int j = (int) (v.size() - 1); j >= 0; j--) {
        if (c == v[j]) {
            i++;
        } else break;
    }
    return i;
}

int go(char c, vector<char> &v) {
    while (v.back() != c) {
        v.pop_back();
    }
}

int main() {
    char currentState = 'L';
    vector<char> v;
    ifstream io("input.txt");
    int res = 0;
    for (char c; io >> c;) {
        //cout << c;
        if (c == 'B') {
            res++;
            continue;
        }
        v.push_back(c);
    }
    std::reverse(v.begin(), v.end());
    while (v.size() > 0) {
        go(currentState, v);
        if (v.size() > 0) {
            int sletters = howmuchsameletters(currentState, v);
            if (sletters >= 2) {
                for (int i = 0; i < sletters; ++i) {
                    v.pop_back();
                }
                changeside(currentState);
            } else
                v.pop_back();
            res++;
        }
    }


    ofstream o;
    o.open("output.txt");
    o << res;
    o.close();
    //cout << endl << res;

    return 0;
}