/*
Things to notice:
1. do not calculate useless values
2. do not use similar names
 
Things to check:
1. submit the correct file
2. time (it is log^2 or log)
3. memory
4. prove your naive thoughts 
5. long long
6. corner case like n=0,1,inf or n=m
7. check if there is a mistake in the ds or other tools you use
8. fileio in some oi-contest

9. module on time 
10. the number of a same divisor in a math problem
11. multi-information and queries for dp and ds problems
*/
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
const int mod=998244353;
const int inf=0x3f3f3f3f;
const int INF=1e18;
string s; 
int fib[105],n;
const int B=30;
int dp[31][150005]; 
int ans=inf;
vector <array<int,3> > stk;
void dfs(int l,int r,int d)
{

	stk.pb({l,r,d});
	if(l==r)
	{
		int idx=dp[d][1];
		int u=-1,now=1;
		for(int i=stk.size()-1;i>=1;i--)
		{
			if(stk[i][1]<stk[i-1][1])
			{
				if(dp[stk[i][2]-1][idx]>n) 
				{
					u=stk[i][2]-1;
					break;
				}
				else idx=dp[stk[i][2]-1][idx],now+=fib[stk[i][2]-1];
			}
		}
		if(u!=-1)
		{
			while(1)
			{
				if(u<=1)
				{
					if(dp[u][idx]<=n) now++;
					break;
				}
				if(dp[u-1][idx]<=n) now+=fib[u-1],idx=dp[u-1][idx],u-=2;
				else u--;
			}
			ans=min(ans,now+1);
		}
	}
	else
	{
		int mid=l+fib[d-1]-1;
		dfs(l,mid,d-1),dfs(mid+1,r,d-2);
	}
	stk.pop_back();
}
void solve()
{
//	for(int i=0;i<150000;i++) s+='a';
	cin>>s;
	if(s.size()==1)
	{
		cout<<"1\n";
		return;
	}
	s='.'+s;
	n=s.size()-1;
	for(int i=1;i<=n;i++)
	{
		dp[0][i]=(s[i]=='b'?i+1:i);
		dp[1][i]=(s[i]=='a'?i+1:i);
	}
	for(int k=2;k<=B;k++) for(int i=1;i<=n;i++)
	{
		if(dp[k-1][i]>n) dp[k][i]=n+1;
		else dp[k][i]=dp[k-2][dp[k-1][i]];
	}
	fib[0]=1,fib[1]=1;
	for(int i=2;i<=B;i++) fib[i]=fib[i-1]+fib[i-2];
	dfs(1,fib[B],B);
	cout<<ans<<"\n"; 
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int _=1;
//	cin>>_;
	while(_--) solve();
	return 0;
}