import std.stdio, std.array, std.conv, std.string, std.algorithm, std.math, std.regex;

void main(){
    string s;
    s = readln().chomp();
    auto pos = s.indexOf("c");
    if(pos != -1){
        s = s[pos..$];
        pos = s.lastIndexOf("w");
        if(pos != s.indexOf("w")){
            writeln(pos+1);
            return;
        }
    }
    writeln(-1);
}



// 読み込み用
T readOne(T=size_t)(){
    return readln().chomp().split[0].to!T();
}

T[] readLine(T=size_t)(string op=" "){
	T[] ol;
	foreach(string elm; readln().chomp().split(op)){
		ol ~= elm.to!T();
	}
	return ol;
}