#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <utility>
#include <vector>
#include <stack>

using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
#define rep1(i, n) for (int i = 1; i < n + 1; i++)
#define all(A) A.begin(), A.end()
#define itr(A, l, r) A.begin() + l, A.begin() + r
#define debug(var) cout << #var << " = " << var << endl;
typedef long long ll;

int main(void)
{
    string s;
    cin >> s;
    int state = 0;
    int ans = 0;
    int n = s.size();
    rep(i, n)
    {
        char c = s[i];
        if (c == 'c' && state == 0)
        {
            state = 1;
        }
        else if (c == 'w' && state == 1)
        {
            state = 2;
        }
        else if (c == 'w' && state == 2)
        {
            ans++;
            state = 3;
        }
        if (1 <= state && state <= 2)
        {
            ans++;
        }
    }
    if (state < 3)
    {
        cout << -1 << endl;
    }
    else
    {
        cout << ans << endl;
    }
}