print((function (f, s)
	return f(s)
end)(function (s)
	local n,a,b,c = #s+1,1,1,1
	while true do
		a = s:find("c", a)
		if a == nil then break end
		b = s:find("w", a)
		if b == nil then break end
		c = s:find("w", b+1)
		if c == nil then break end
		if c-a+1 < n then n = c-a+1 end
		a = a+1
	end
	if n > #s then n = -1 end
	return n
end, io.stdin:read("*l")))