#include <bits/stdc++.h>
#define rep(i,n) for(ll i = 0; i < n; i++) //[0,n)
#define srep(i,a,b) for(ll i = a; i < b; i++) //[a,b)
#define all(A) (A).begin(),(A).end()
#define rall(A) (A).rbegin(),(A).rend()
#define pmt(A) next_permutation(all(A))
using namespace std;
using ll = long long;
using ull = unsigned long long;
using P = pair<ll,ll>;
using pq = priority_queue<P,vector<P>,greater<P>>;
ll inf = 1LL<<60;
int iinf = (int)1e9+1;
int mod9 = 998244353;
int mod1 = 1000000007;
struct Edge { int to; int cost; int from; };
bool compe(const Edge &e,const Edge &e2){ return e.cost < e2.cost; }
using Graph = vector<vector<ll>>;
using SGraph = vector<set<ll>>;
template <typename T>
int siz(T& a){return (int)a.size();}
ll squa(ll a){ return a*a; }
ll ceil(ll a,ll b){ return (a+b-1)/b; }

//Validation Test
int main(void){
	int N,K; cin >> N >> K;
	string S; cin >> S;

	assert(1 <= N && N <= 300000);
	assert(0 <= K && K <= N);

	rep(i,N-1) if(S[i] == 'C') assert(S[i+1] != 'P');
	
	int cnt = 0;
	rep(i,N) if(S[i] == 'N') cnt++;
	assert(cnt >= K);
	return 0;
}