#include<iostream>
using namespace std;

int main(){
    int minLength = 101, length = 0;
    int status = 0; // 'nothing' - 0 c' - 1 : 'w' - 2 : 'w' - 3
    char c;
    bool incww = false;
    for(; cin >> c;){
        if(incww)   length++;
        if(!incww && c == 'c'){
            incww = true;
            status = 1;
            length = 1;
        }

        if(incww && c == 'w'){
            status++;
            if(status == 3){
                minLength = min(minLength, length);
                status = 0;
                length = 0;
                incww = false;
            }
        }
    }

    if(minLength == 101)    minLength = -1;

    cout << minLength << endl;
    return 0;
}