import collections
S = input()
lst = ['KUROI?'.index(c) for c in S if c in 'KUROI?']
m = len(lst) // 5
dp = collections.defaultdict(int)
dp[0,0,0,0] = 0
for c in lst:
    dp_c = dp.copy()
    for (k0, k1, k2, k3), val in dp_c.items():
        if (c == 4 or c == 5) and k3 > val and dp[k0, k1, k2, k3] <= val:
            dp[k0, k1, k2, k3] = val + 1
        if (c == 3 or c == 5) and k2 > k3:
            new_key = (k0, k1, k2, k3 + 1)
            if (new_key not in dp) or dp[new_key] < val:
                dp[new_key] = val
        if (c == 2 or c == 5) and k1 > k2:
            new_key = (k0, k1, k2 + 1, k3)
            if (new_key not in dp) or dp[new_key] < val:
                dp[new_key] = val
        if (c == 1 or c == 5) and k0 > k1:
            new_key = (k0, k1 + 1, k2, k3)
            if (new_key not in dp) or dp[new_key] < val:
                dp[new_key] = val
        if (c == 0 or c == 5) and m > k0:
            new_key = (k0 + 1, k1, k2, k3)
            if (new_key not in dp) or dp[new_key] < val:
                dp[new_key] = val
print(max(dp.values()))