#include<bits/stdc++.h>
using namespace std;

int main(){
	string s; cin>>s;
	vector<int>c,w;
	for(int i=0;i<s.size();++i){
		if(s.at(i)=='c')c.emplace_back(i);
		else if(s.at(i)=='w')w.emplace_back(i);
	}
	int ans=101;
	for(auto&&C:c){
		auto w1=lower_bound(w.begin(),w.end(),C);
		if(w1>=w.end()-1)continue;
		ans=min(ans,*(w1+1)-C+1);
	}
	cout<<(ans!=101?ans:-1)<<"\n"s;
}