s=input()
l=len(s)
m=1000
i=c=w=v=0
while i<l:
 if s[i]=='c':c=i+1
 if w and s[i]=='w':v=i
 if s[i]=='w':w=i
 if c and w and v:m=min(m,v-c+2);i=c;c=w=v=0
 i+=1
print(m if m!=1000 else -1)