#include <iostream>
#include <string>
using namespace std;

int main() {
	int state,ans; //state 0:NO 1:c 2:w 3:w
	string S;
	cin >> S;

	int i = 0;
	ans = 0;
	state = 0;
	while(S[i]) {
		switch(state) {
			case 0:
				if(S[i] == 'c') state = 1;
				break;
			case 1:
				if(S[i] == 'w') state = 2;
				break;
			case 2:
				if(S[i] == 'w') state = 3;
				break;
		}
		if(state != 0) ans++;
		if(state == 3) break;
		i++;
	}

	if(state == 3) cout << ans << endl;
	else cout << "-1" << endl;

	return 0;
}