S=input()
c_index,cw_index=None,None
ans=float('inf')
for i,k in enumerate(S):
    if k=="c":
        c_index=i
    elif k=="w":
        if cw_index is not None:
            ans=min(ans,i-cw_index+1)
        if c_index is not None:
            cw_index=c_index
print([ans,-1][ans==float('inf')])