#define	_USE_MATH_DEFINES
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cfloat>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <string>
#include <set>
#include <complex>
#include <utility>
#include <numeric>
#define  rep(i,n) for(int i=0;i<(n);i++)
#define  REP(i,a,n) for(int i=a;i<(n);i++)
#define  rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define  VI	vector<int>
#define	 VS vector<string>
#define  all(a) (a).begin(),(a).end()
#define  debug(x) cout<<#x<<": "<<x<<endl
using namespace std;
typedef pair<int,int> P;
typedef long long ll;

const int INF=1000000;
char fi[101][101];
int d[21][21];
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};
int N,M;
int sx,sy;
int gx,gy;
int w,h;
int ans;

int dx[4]={0,0,-1,1};
int dy[4]={-1,1,0,0};
const int MAX_V=100;
const int MAX_N=100;
char o[3]={'+','-','*'};
#define md 1000003
set<string> a;
ll po(ll x,int n){
	ll r=1;
	while(n>0){
		if(n&1)
		r=(r*x)%md;
		x=(x*x)%md;
		n>>=1;
	}
	return r;
}

int main(){

	string s;
	cin>>s;
	int k=0;
	string a="";
	for(int i=s.size()-1;i>=0;i--){
		if(k==0&&s[i]=='w'){
			k++;
			a+=s[i];
		}
		else if(k==1){
			if(s[i]=='w')
				k++;
			a+=s[i];
		}
		else if(k==2){
			if(s[i]=='c'){
				a+=s[i];
				k++;
				break;
			}
			else
				a+=s[i];
		}
	}
	if(k==3)
	cout<<a.size()<<endl;
	else
	cout<<-1<<endl;
	
}