#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin() , v.end()
#define REP(i, x, n) for(int i = x; i < n; i++)


int main(){
    string s; cin >> s;
    int rel = 101, cnt = 0, flg = 0;
    rep(i, s.size()){
        if(s[i] == 'c' && flg == 0) flg++;
        if(flg) cnt++;
        if(flg == 2 && s[i] == 'w') rel = min(cnt,rel) ,cnt = 0, flg = 0;
        if(flg == 1 && s[i] == 'w') flg++;
    }
    if(rel == 101) rel = -1;
    cout << rel << endl;
}