import std;

void main () {
    string S = readln.chomp;
    const int N = S.length.to!int;

    bool good (string X) {
        return (X[0] == X[1] && X[0] != X[2]) || (X[1] == X[2] && X[0] != X[1]);
    }
    int ans = 0;
    foreach (i; 0 .. N - 2) {
        if (good(S[i .. i + 3])) {
            ans++;
        }
    }

    writeln(ans);
}

void read (T...) (string S, ref T args) {
    import std.conv : to;
    import std.array : split;
    auto buf = S.split;
    foreach (i, ref arg; args) {
        arg = buf[i].to!(typeof(arg));
    }
}