#include <iostream>

using namespace std;

int main (){
    string journals;
    cin >> journals;

    char sign = journals[0];
    int count = 0;
    for (size_t i = 0; i < journals.size(); i +=2) {
        if(sign == journals[i])
            continue;
        else {
            while(journals[i] != sign && i < journals.size()) {
                i +=2;
            }
            count++;
        }
    }

    cout << count << '\n';

    return 0;
}