s=input()

a=''
count=0
for i in range(len(s)):
    if a=='' and s[i]=='c':
        a+='c'
        count+=1
    elif a=='c' and s[i]=='w':
        a+='w'
        count+=1
    elif a=='cw' and s[i]=='w':
        a+='w'
        count+=1
        break
    elif a=='c' or a=='cw':
        count+=1

if count==len(s) and a!='cww':
    print(-1)
else:
    print(count)