#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
using namespace std;



int main(void){

  int i,l,r,n;
  string s;
  cin>>s;

  n=s.length();
  for(i=0;i<n;i++){
    if(s[i]=='w') break;
  }
  l=i;
  r=n-l;

  if(r>=l) cout<<l-1<<endl;
  else cout<<r<<endl;
  return 0;
}