#include <bits/stdc++.h>
#define rep(i, a, b) for (int i = a; i <= b; i++)
#define per(i, a, b) for (int i = a; i >= b; i--)
using namespace std;

typedef unsigned long long ull;
typedef pair <int, int> pii;
typedef long long ll;

template <typename _T>
inline void read(_T &f) {
    f = 0; _T fu = 1; char c = getchar();
    while (c < '0' || c > '9') { if (c == '-') { fu = -1; } c = getchar(); }
    while (c >= '0' && c <= '9') { f = (f << 3) + (f << 1) + (c & 15); c = getchar(); }
    f *= fu;
}

template <typename T>
void print(T x) {
    if (x < 0) putchar('-'), x = -x;
    if (x < 10) putchar(x + 48);
    else print(x / 10), putchar(x % 10 + 48);
}

template <typename T>
void print(T x, char t) {
    print(x); putchar(t);
}

const int N = 150005, M = 30;

int tr[N][M + 5], fib[M + 5];
char c[N];
int n, ans = 1e9;

pii solve(int fid, int fpos, int npos) {
    if (fid <= 1) return make_pair(tr[npos][fid], 1);
    if (fpos == 1) {
        if (tr[npos][fid - 1] == n + 1) {
            return solve(fid - 1, 1, npos);
        } else {
            pii t = solve(fid - 2, 1, tr[npos][fid - 1]);
            t.second += fib[fid - 1];
            return t;
        }
    }
    if (fpos <= fib[fid - 1]) {
        pii t = solve(fid - 1, fpos, npos);
        if (t.first == n + 1) return t;
        t = solve(fid - 2, 1, t.first);
        t.second += fib[fid - 1] - fpos + 1;
        return t;
    }
    return solve(fid - 2, fpos - fib[fid - 1], npos);
}

int main() {
    scanf("%s", c + 1); n = strlen(c + 1);
    for (int i = 0; i <= M; i++) tr[n + 1][i] = n + 1;
    fib[0] = fib[1] = 1;
    for (int i = 1; i <= n; i++) {
        if (c[i] == 'a') {
            tr[i][0] = i;
            tr[i][1] = i + 1;
        } else {
            tr[i][0] = i + 1;
            tr[i][1] = i;
        }
    }
    for (int j = 2; j <= M; j++) {
        fib[j] = fib[j - 1] + fib[j - 2];
        for (int i = 1; i <= n; i++) tr[i][j] = tr[tr[i][j - 1]][j - 2];
    }
    for (int i = 1; i <= fib[M]; i++) {
        pii res = solve(M, i, 1);
        if (res.first != n + 1) break;
        ans = min(ans, res.second);
    }
    print(ans, '\n');
    return 0;
}