#include<iostream>
#include<string>
using namespace std;
int main() {
	string S;
	int cwwFlag[2] = { 0,0 };
	int cwwCounter[2] = { 0,0 };
	int cwwMin = 101;
	cin >> S;
	for (int i = 0; i < S.length(); i++) {
		if (S[i] == 'c') {
			if (cwwFlag[0] == 1) cwwCounter[0] = 0;
			else cwwFlag[0] = 1;
		}
		if (cwwFlag[0] == 1) cwwCounter[0]++;
		if (cwwFlag[1] == 1) cwwCounter[1]++;
		if (S[i] == 'w') {
			if (cwwFlag[1] == 1) {
				if (cwwCounter[1] < cwwMin)
					cwwMin = cwwCounter[1];
				cwwCounter[1] = 0;
				cwwFlag[1] = 0;
			}
			if (cwwFlag[0] == 1) {
				cwwCounter[1] = cwwCounter[0];
				cwwFlag[1] = 1;
				cwwCounter[0] = 0;
				cwwFlag[0] = 0;
			}
		}
	}
	if (cwwMin == 101) cwwMin = -1;
	cout << cwwMin << endl;
	return 0;
}