#include<bits/stdc++.h>
#define rep(i,s,n) for (int i = (int)(s); i < (int)(n); i++)
#define all(v) begin(v),end(v)
using namespace std;
using ll = long long;
using vl=vector<ll>;
using vvl=vector<vl>;
using vvvl=vector<vvl>;
using pll=pair<ll,ll>;
using vp=vector<pll>;
bool chmin(auto &a, auto b){ return a > b ? a = b, 1 : 0; }
bool chmax(auto &a, auto b){ return a < b ? a = b, 1 : 0; }
constexpr ll INF=1LL<<60;

ll solve(string s){
	ll n=s.size();
	s+=s[0];
	ll t=2;
	rep(i,0,n)if(s[i]=='R'&&s[i+1]=='R') t=1;
	if(t==2){
		vl a;
		rep(i,0,n)if(s[i]=='L'&&s[i+1]=='L') a.emplace_back(i);
		assert((ll)a.size()==4);
		vl b(4);
		rep(i,0,4) b[i]=((i==3?a[0]+n:a[i+1])-a[i])>>1;
		ll rs=0;
		rep(i,0,2){
			ll mx=0;
			rep(j,0,2){
				ll sm=1;
				rep(k,0,2) sm+=b[(2*j+k+i)%4];
				chmax(mx,sm);
			}
			rs+=mx;
		}
		if(b[0]==0&&b[2]==0&&b[1]==b[3]&&b[1]>0) rs++;
		if(b[1]==0&&b[3]==0&&b[0]==b[2]&&b[0]>0) rs++;
		rs<<=1;
		return rs;
	}
	auto f=[&](ll l,ll r){
		vl b;
		while(1){
			l=(l+2)%n;
			if(l==r) break;
			b.emplace_back(s[l]=='L'?1:-1);
		}
		return b;
	};
	vl b,c;
	rep(i,0,n)if(s[i]=='R'&&s[i+1]=='R'){
		ll x=(i+1)%n,y=x;
		while(1){
			if(s[x]=='L'&&s[x+1]=='L') break;
			x=(x-2+n)%n;
		}
		while(1){
			if(s[y]=='L'&&s[y+1]=='L') break;
			y=(y+2)%n;
		}
		b=f(x,y),c=f(y,x);
		reverse(all(c));
		break;
	}
	if(b.size()<c.size()){
		swap(b,c);
		for(auto &v:b) v=-v;
		for(auto &v:c) v=-v;
	}
	ll sb=b.size(),sc=c.size();
	vl yb(sb+1),yc(sc+1);
	rep(i,0,sb) yb[i+1]=yb[i]+b[i];
	rep(i,0,sc) yc[i+1]=yc[i]+c[i];
	auto cost=[&](ll i,ll j)->ll
	{
		return yb[i]-yc[j]+1+(i>0&&b[i-1]==-1||i<sb&&b[i]==1);
	};
	vl dp(sc+1,INF);
	dp[0]=0;
	rep(i,0,sb+1){
		vl DP(sc+1,INF);
		rep(j,0,sc+1) chmin(DP[j],max(dp[j],cost(i,j)));
		if(i!=0) rep(j,0,sc) chmin(DP[j+1],max(dp[j],cost(i,j+1)));
		dp=DP;
	}
	return (sb+1)*2+sb+sc+2*dp[sc]+yc[sc]-yb[sb];
}

int main(){
	cin.tie(0)->sync_with_stdio(0);
	
	string s;
	cin>>s;
	cout<<solve(s)<<endl;
}