S = input()
c = ""
w = [0,0]
indexw = [i for i, x in enumerate(S) if x == "w"]
indexc = [i for i, x in enumerate(S) if x == "c"]
leng = []

if S.count("cww") > 0:
    print(3)
else:
    for i in S:
        if i == "c":
            if w[0] != 0 and w[1] == 0:
                pass
            else:
                c = indexc[0]
                indexc.pop(0)
                for i in range(len(indexw)):
                    if indexw[0] < c:
                        indexw.pop(0)
                    else:
                        break
        elif i == "w" and w[0] != 0:
            w[1] = indexw[0]
            leng.append(w[1]-c+1)
            c = 0
            w = [0,0]
        elif i == "w" and c != "":
            w[0] = indexw[0]
            indexw.pop(0)
    if len(leng) <= 0:
        print(-1)
    else:
        print(min(leng))