#include<iostream>
#include<vector>
#include<set>
#include<map>
#include<list>
#include<stack>
#include<queue>
#include<bitset>
#include<array>
#include<algorithm>
#include<cstdio>
#include<string>
#include<cstdlib>
#include<numeric>
#define D int
#define U unsigned
using namespace std;
D n, m,a, b, d, e;
D i, j, k;
char c,f;
bool g, h;
string s;
D ans;
char ta[] = { 'K','U','R','O','I' };
int main() {
	cin >> s;
	vector<int> p[6];
	for (i = 0; i < 20; i++) {
		p[0].push_back(0);
	}
	i = 0;
	for (auto &x : s) {
		for (j = 4; j >= 0; j--) {
			if (!p[j].empty()&&x==ta[j]) {
				x = ' ';
				p[j].pop_back();
				p[j + 1].push_back(i);
				break;
			}
		}
		i++;
	}
	i = 0;
	for (auto x : s) {
		if (x == '?') {
			for (j = 4; j >= 0; j--) {
				auto it = p[j].begin();
				for (auto y : p[j]) {
					if (i < y)
						break;
					it++;
				}
				if (it!=p[j].begin()) {
					it--;
					p[j].erase(it);
					auto it2 = p[j + 1].begin();
					for (auto y : p[j+1]) {
						if (i < y)
							break;
						it2++;
					}
					p[j + 1].insert(it2,i);
					break;
				}
			}
		}
		for (j = 4; j >= 0; j--) {
			if (!p[j].empty() && x == ta[j]) {
				p[j].pop_back();
				p[j + 1].push_back(i);
				break;
			}
		}
		i++;
	}
	cout << p[5].size() << endl;
}