s = input()
c = False
w=0
start = 0
for i in range(len(s)):
    if w==0 and s[i]=="c":
        c=True
        start = i

    if c==True and s[i]=="w":
        w+=1
        
    if w==2:
        break

length= i-start+1

if w==2:
    print(length)
else:
    print(-1)