#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define chmin(a, b) ((b) < a && (a = (b), true))
#define chmax(a, b) (a < (b) && (a = (b), true))
using namespace std;
typedef long long ll;

#include <bits/stdc++.h>
#define GET_MACRO(a, b, c, NAME, ...) NAME
#define rep(...) GET_MACRO(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define rep2(i, a) rep3 (i, 0, a)
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define repr(...) GET_MACRO(__VA_ARGS__, repr3, repr2)(__VA_ARGS__)
#define repr2(i, a) repr3 (i, 0, a)
#define repr3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define chmin(a, b) ((b) < a && (a = (b), true))
#define chmax(a, b) (a < (b) && (a = (b), true))
using namespace std;
typedef long long ll;

int dp[101][22][22][22][22]; // pos, k, u, r, o => i

int main() {
	string s;
    cin >> s;
    int N = s.length();
    const int inf = 1e9;
    rep (i, 101) rep (j, 21) rep (k, 21) rep (l, 21) rep (m, 21) dp[i][j][k][l][m] = -inf;
    dp[0][0][0][0][0] = 0;
    rep (i, N) rep (j, 21) rep (k, 21) rep (l, 21) rep (m, 21) {
    	chmax(dp[i + 1][j][k][l][m], dp[i][j][k][l][m]);
    	if (s[i] == 'K') {
    		chmax(dp[i + 1][j + 1][k][l][m], dp[i][j][k][l][m]);
    	} else if (s[i] == 'U') {
    		if (j) chmax(dp[i + 1][j - 1][k + 1][l][m], dp[i][j][k][l][m]);
    	} else if (s[i] == 'R') {
    		if (k) chmax(dp[i + 1][j][k - 1][l + 1][m], dp[i][j][k][l][m]);
    	} else if (s[i] == 'O') {
    		if (l) chmax(dp[i + 1][j][k][l - 1][m + 1], dp[i][j][k][l][m]);
    	} else if (s[i] == 'I') {
    		if (m) chmax(dp[i + 1][j][k][l][m - 1], dp[i][j][k][l][m] + 1);
    	} else if (s[i] == '?') {
    		chmax(dp[i + 1][j + 1][k][l][m], dp[i][j][k][l][m]);
    		if (j) chmax(dp[i + 1][j - 1][k + 1][l][m], dp[i][j][k][l][m]);
    		if (k) chmax(dp[i + 1][j][k - 1][l + 1][m], dp[i][j][k][l][m]);
    		if (l) chmax(dp[i + 1][j][k][l - 1][m + 1], dp[i][j][k][l][m]);
    		if (m) chmax(dp[i + 1][j][k][l][m - 1], dp[i][j][k][l][m] + 1);
    	}
    }
    int ans = 0;
    rep (j, 21) rep (k, 21) rep (l, 21) rep (m, 21) {
    	chmax(ans, dp[N][j][k][l][m]);
    }
    cout << ans << endl;
    return 0;
}