#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;

string s;
int N;
typedef tuple<int, int, int, int, int, int> P;

map<P, int> dp;

int dfs(int i, int j, int k, int l, int m, int n) {
	if (i < 0 || j < 0 || k < 0 || l < 0 || m < 0 || n < 0) return 0;
	P key(i, j, k, l, m, n);
	if (i == N) return n;
	if (dp.count(key)) return dp[key];
	int res = dfs(i + 1, j, k, l, m, n);
	if (s[i] == 'K') {
		chmax(res, dfs(i + 1, j + 1, k, l, m, n));
	} else if (s[i] == 'U') {
		chmax(res, dfs(i + 1, j - 1, k + 1, l, m, n));
	} else if (s[i] == 'R') {
		chmax(res, dfs(i + 1, j, k - 1, l + 1, m, n));
	} else if (s[i] == 'O') {
		chmax(res, dfs(i + 1, j, k, l - 1, m + 1, n));
	} else if (s[i] == 'I') {
		chmax(res, dfs(i + 1, j, k, l, m - 1, n + 1));
	} else if (s[i] == '?') {
		chmax(res, dfs(i + 1, j + 1, k, l, m, n));
		chmax(res, dfs(i + 1, j - 1, k + 1, l, m, n));
		chmax(res, dfs(i + 1, j, k - 1, l + 1, m, n));
		chmax(res, dfs(i + 1, j, k, l - 1, m + 1, n));
		chmax(res, dfs(i + 1, j, k, l, m - 1, n + 1));
	}
	return dp[key] = res;
}

int main() {
	cin >> s;
	N = s.length();
	cout << dfs(0, 0, 0, 0, 0, 0) << endl;
	return 0;
}