from collections import defaultdict


def solve():
    SS = input()
    S = [c for c in SS if c in 'KUROI?']

    dp2 = defaultdict(lambda: -1)

    # dp[x, k, u, r, o] = 次に見るのが x 文字目で、 kまで: k個、uまで: u個、rまで: r個、oまで: o個 のとき、i までできた数
    dp2[0, 0, 0, 0] = 0
    ma = 0

    for x, c in enumerate(S):
        dp1 = dp2
        dp2 = defaultdict(lambda: -1, dp1)
        for kuro in dp1:
            now = dp1[kuro]
            k, u, r, o = kuro

            if c == 'K' or c == '?':
                dp2[k + 1, u, r, o] = max(dp2[k + 1, u, r, o], now)
            if (c == 'U' or c == '?') and k:
                dp2[k - 1, u + 1, r, o] = max(dp2[k - 1, u + 1, r, o], now)
            if (c == 'R' or c == '?') and u:
                dp2[k, u - 1, r + 1, o] = max(dp2[k, u - 1, r + 1, o], now)
            if (c == 'O' or c == '?') and r:
                dp2[k, u, r - 1, o + 1] = max(dp2[k, u, r - 1, o + 1], now)
            if (c == 'I' or c == '?') and o:
                dp2[k, u, r, o - 1] = max(dp2[k, u, r, o - 1], now + 1)
                ma = max(ma, now + 1)
    print(ma)


if __name__ == '__main__':
    solve()