# 定数倍高速化じゃ通らないかも...

def solve():
    SS = input()
    S = [c for c in SS if c in 'KUROI?']
    EM = len(S) // 5

    dp2 = {(0, 0, 0, 0): 0}

    # 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
    ma = 0

    for x, c in enumerate(S):
        dp1 = dp2
        dp2 = {}
        for kuro in dp1:
            now = dp1[kuro]
            k, u, r, o = kuro

            if c == 'K':
                if k < EM:
                    nn = k + 1, u, r, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
            elif c == 'U':
                if k and u < EM:
                    nn = k - 1, u + 1, r, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
            elif c == 'R':
                if u and r < EM:
                    nn = k, u - 1, r + 1, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
            elif c == 'O':
                if r and o < EM:
                    nn = k, u, r - 1, o + 1
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
            elif c == 'I':
                if o:
                    ma = max(ma, now + 1)
                    nn = k, u, r, o - 1
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now + 1)
                    else:
                        dp2[nn] = now + 1
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
            elif c == '?':
                if k < EM:
                    nn = k + 1, u, r, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
                if k and u < EM:
                    nn = k - 1, u + 1, r, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
                if u and r < EM:
                    nn = k, u - 1, r + 1, o
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
                if r and o < EM:
                    nn = k, u, r - 1, o + 1
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now)
                    else:
                        dp2[nn] = now
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
                if o:
                    ma = max(ma, now + 1)
                    nn = k, u, r, o - 1
                    if nn in dp2:
                        dp2[nn] = max(dp2[nn], now + 1)
                    else:
                        dp2[nn] = now + 1
                else:
                    if kuro in dp2:
                        dp2[kuro] = max(dp2[kuro], now)
                    else:
                        dp2[kuro] = now
    print(ma)


if __name__ == '__main__':
    solve()