file = open('23.txt')
s = file.readline()
l = 0
kx = 0
ky = 0
ans = 10**10
for r in range(len(s)):
    if s[r] == 'X':
        kx += 1
    if s[r] == 'Y':
        ky += 1
    while kx >= 500 and ky == 0:
        if s[l] == 'X':
            kx -= 1
        l += 1
        ans = min(ans, r - l + 1)
    if ky != 0:
        l = r
        ky = 0
print(ans)