#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;
constexpr ll inf=1LL<<30;

int main(){
    cin.tie(0)->sync_with_stdio(0);

    string s;
    cin>>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;
        cout<<rs<<endl;
    }
    else{
        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,y=i+1;
            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));
//            for(auto &v:c) v=-v;
            break;
        }
        if(b.size()<c.size()) swap(b,c);
        ll sb=b.size();
        ll sc=c.size();
        vl ys(sb+1),yu(sc+1);
        {
            ll y=0;
            rep(i,0,sb){
                y+=b[i];
                ys[i+1]=y;
            }
        }{
            ll y=0;
            rep(i,0,sc){
                y+=c[i];
                yu[i+1]=y;
            }
        }
        vl dp(sc+1,INF);
        dp[0]=0;
        rep(I,0,sb+1){
            ll y=ys[I];
            vl DP(sc+1,INF);
            rep(i,0,sc+1) chmin(DP[i],max(dp[i],y-yu[i]+1));
			if(I!=0)rep(i,0,sc) chmin(DP[i+1],max(dp[i],y-yu[i+1]+1));
            dp=DP;
        }
        ll rs=sb+1<<1;
		rs+=sb+sc;
        rs+=2*dp[sc]+yu[sc]-ys[sb];
        cout<<rs<<endl;
    }
}