s,f=input(),0
r=range
a=l=len(s)
for i in r(0,l):
    for j in r(i,l):
        if (s[i],s[j])==('c','w') and 'w' in s[i+1:j]:f,a=1,min(a,j-i+1)
print(a if f else -1)