#include<bits/stdc++.h>
#define int long long
#define mod 998244353ll
#define pii pair<int,int>
#define fi first
#define se second
#define mems(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define db double
using namespace std;
const int maxn=150010;
const int inf=1e18;
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch-48);ch=getchar();}
	return x*f;
}
bool Mbe;

int n,m=6,ans=inf;
char s[maxn];
struct nd{
	int len;
	pii pre[maxn],suf[maxn];
}f[32];
nd merge(nd u,nd v){
	nd res;res.len=u.len+v.len;
	for(int i=1;i<=n;i++){
		res.suf[i]=u.suf[i].fi==n+1?u.suf[i]:make_pair(v.suf[u.suf[i].fi].fi,u.len+v.suf[u.suf[i].fi].se);
		res.pre[i]=v.pre[i].fi==0?v.pre[i]:make_pair(u.pre[v.pre[i].fi].fi,v.len+u.pre[v.pre[i].fi].se);
		if(u.pre[i].fi==0&&v.suf[i+1].fi==n+1)ans=min(ans,u.pre[i].se+v.suf[i+1].se);
	}
	return res;
}
void work(){
	scanf("%s",s+1);n=strlen(s+1);
	if(n==1){puts("1");return ;}
	for(int i=1;i<=n;i++){
		if(s[i]=='a'){
			f[1].pre[i]={i-1,1},f[1].suf[i]={i+1,1};
			f[0].pre[i]=f[0].suf[i]={i,0};
		}
		else{
			f[0].pre[i]={i-1,1},f[0].suf[i]={i+1,1};
			f[1].pre[i]=f[1].suf[i]={i,0};
		}
	}
	f[0].len=f[1].len=1;
	for(int i=2;i<=m;i++)f[i]=merge(f[i-1],f[i-2]);
	// for(int j=2;j<=m;j++){
		// cout<<j<<" "<<f[j].len<<"\n";
		// for(int i=1;i<=n;i++)cout<<f[j].pre[i].fi<<" "<<f[j].pre[i].se<<" "<<f[j].suf[i].fi<<" "<<f[j].suf[i].se<<"\n";
	// }
	printf("%lld\n",ans);
}

// \
444

bool Med;
int T;
signed main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	
//	ios::sync_with_stdio(0);
//	cin.tie(0);cout.tie(0);
	
//	cerr<<(&Mbe-&Med)/1048576.0<<" MB\n";
	
	T=1;
	while(T--)work();
}