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

//#define int long long
#define f(i,a,b) for(int i = (a); i < (b); ++i)

signed main() {
    ios_base::sync_with_stdio(0);
    string s; cin >> s;
    int n = s.size();
    int ans = 0;
    f(i,1,n) if (s[i] == s[i-1])ans++;

    cout << ans << endl;

    return 0;
}