#include<iostream>
#include<string>
using namespace std;
int main() {
	string S;
	int cwwFlag[20];
	int cwwCounter[20];
	cwwCounter[0] = 101;
	cwwFlag[0] = 0;
	for (int i = 1; i < 20; i++) {
		cwwCounter[i] = 0;
		cwwFlag[i] = 0;
	}
	cin >> S;
	for (int i = 0; i < S.length(); i++) {
		if (S[i] == 'c') {
			cwwFlag[0]++;
			cwwFlag[ cwwFlag[0] ]++;
		}
		if (cwwFlag[0] > 0) {
			for (int j = 1; j <= cwwFlag[0]; j++) {
				cwwCounter[j]++;
				if (S[i] == 'w') {
					cwwFlag[j]++;
					if (cwwFlag[j] == 3) {
						if (cwwCounter[j] < cwwCounter[0])
							cwwCounter[0] = cwwCounter[j];
						for (int k = j; k < cwwFlag[0]; k++) {
							cwwCounter[k] = cwwCounter[k + 1];
							cwwFlag[k] = cwwFlag[k + 1];
						}
						cwwCounter[ cwwFlag[0] ] = 0;
						cwwFlag[ cwwFlag[0] ] = 0;
						j--;
						cwwFlag[0]--;
					}
				}
			}
		}
	}
	if (cwwCounter[0] == 101) cwwCounter[0] = -1;
	cout << cwwCounter[0] << endl;
	return 0;
}