a = 0
b = float('inf')
d = 0
for i, c in enumerate(raw_input()):
    if c == 'c':
        a = 1
        d = i
    elif c == 'w':
        a += 1
        if a == 3:
            b = min(b, i-d+1)
print b if b != float('inf') else -1