#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int v, c; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int dp[101][51][34][26], _dp[101][51][34][26];

int main() {
	for (int k = 0; k <= 100; k++)
		for (int u = 0; u <= 50; u++)
			for (int r = 0; r <= 33; r++)
				for (int o = 0; o <= 25; o++)
					dp[k][u][r][o] = -1;
	dp[0][0][0][0] = 0;
	string S; cin >> S;
	for (int i = 0; i < S.length(); i++) {
		char c = S[i];
		for (int k = 0; k <= 20; k++)
		for (int u = 0; u <= 20; u++)
			for (int r = 0; r <= 20; r++)
				for (int o = 0; o <= 20; o++) {
						if (dp[k][u][r][o] == -1) continue;
						if (c == 'K' || c == '?')
							_dp[k + 1][u][r][o] = max(_dp[k + 1][u][r][o], dp[k][u][r][o]);
						if ((c == 'U' || c == '?') && k >= 1)
							_dp[k - 1][u + 1][r][o] = max(_dp[k - 1][u + 1][r][o], dp[k][u][r][o]);
						if ((c == 'R' || c == '?') && u >= 1)
							_dp[k][u - 1][r + 1][o] = max(_dp[k][u - 1][r + 1][o], dp[k][u][r][o]);
						if ((c == 'O' || c == '?') && r >= 1)
							_dp[k][u][r - 1][o + 1] = max(_dp[k][u][r - 1][o + 1], dp[k][u][r][o]);
						if ((c == 'I' || c == '?') && o >= 1)
							_dp[k][u][r][o - 1] = max(_dp[k][u][r][o - 1], dp[k][u][r][o] + 1);
					}
		swap(dp, _dp);
	}
	int maxi = 0;
	for (int k = 0; k <= 100; k++)
		for (int u = 0; u <= 50; u++)
			for (int r = 0; r <= 33; r++)
				for (int o = 0; o <= 25; o++)
					maxi = max(maxi, dp[k][u][r][o]);
	cout << maxi << endl;
}