#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

#define rep(i, a, b) fo(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;

string s;

ll findBack(ll end, ll start)
{
    for(; end > start; end--)
        if(s[end] == s[end-1])
            return end;
    return -1;
}

ll findStart(ll start, ll end)
{
    for(; start < end; start++)
        if(s[start] == s[start+1])
            return start;
    return -1;
}

void fix()
{
    ll start = 0, end = s.size() -1;
    ll moves = 0;
    while(start<= end)
    {
        ll a = findStart(start, end);
        if(a == -1)
        {
            cout << moves << endl;
            return;
        }
        ll b = findBack(end, a);
        if(b == -1)
        {
            cout << moves +1 << endl;
            return;
        }

        moves++;
        start = a+1;
        end = b-1;
    }
    cout << moves << endl;
}



int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
    cin >> s;
    fix();
}