#include <iostream>
using namespace std;
int main() {
    int c=0,w=0;
    char a;
    bool cww=false;
    while (!cww) {
        a = getchar();
        if (a < 97 || 122 < a) break;
        if (c) {
            if (w) {
                if (a == 'w') {
                    cww = true;
                }
            } else if (a == 'w') {
                w++;
            }
            c++;
        } else if (a == 'c') {
            c++;
        }
    }
    if (cww) cout << c << endl;
    else cout << -1 << endl;
    return 0;
}