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 = []

for i in S:
    if i == "c":
        c = indexc[0]
        indexc.pop(0)
        w = [0,0]
        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
    elif i == "w" and c != "":
        w[0] = indexw[0]
        indexw.pop(0)

if len(leng) <= 0:
    print(-1)
else:
    print(min(leng))