#include<iostream>
using namespace std;
int main(){
int count=0;
string s ;
int i;
for(int i=0; i<3;i++){
cin>>s[i];
}
if(s[i] == 'R' && s[i+1]=='R' && s[i+2]=='R' ){
cout<<3;
}else if ( (s[i] == 'R' && s[i+1]=='R' && s[i+2]!='R') || (s[i] != 'R' && s[i+1]=='R' && s[i+2]=='R') ){
cout<<2;
}else if ( (s[i] == 'R' && s[i+1]!='R' && s[i+2]!='R') || (s[i] == 'R' && s[i+1]!='R' && s[i+2]=='R') || (s[i] != 'R' && s[i+1]=='R' && s[i+2]!='R') || (s[i] != 'R' && s[i+1]!='R' && s[i+2]=='R') ){
cout<<1;
}
else if(s[i] != 'R' && s[i+1]!='R' && s[i+2]!='R'){
cout<<0;
}
return 0;
}
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