from collections import defaultdict

S = input()

dp = defaultdict(int)
dp[0, 0, 0, 0] = 0
for c in S:
    pp = dp.copy()
    dp, pp = pp, dp
    for key in pp.keys():
        k, u, r, o = key
        nkey = None
        match c:
            case 'K':
                nkey = (k+1, u, r, o)
            case 'U':
                nkey = (k-1, u+1, r, o)
            case 'R':
                nkey = (k, u-1, r+1, o)
            case 'O':
                nkey = (k, u, r-1, o+1)
            case 'I':
                if o > 0:
                    dp[k, u, r, o-1] = max(dp[k, u, r, o-1], pp[k, u, r, o] + 1)

        if nkey is not None and all(x >= 0 for x in nkey):
            dp[nkey] = max(dp[nkey], pp[key])

        if c == '?':
            nkeys = [
                (k+1, u, r, o),
                (k-1, u+1, r, o),
                (k, u-1, r+1, o),
                (k, u, r-1, o+1),
            ]
            for nkey in nkeys:
                if all(x >= 0 for x in nkey):
                    dp[nkey] = max(dp[nkey], pp[key])

            # for 'I'
            if o > 0:
                dp[k, u, r, o-1] = max(dp[k, u, r, o-1], pp[k, u, r, o] + 1)

ans = max(dp.values())
print(ans)