#include <iostream>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <cmath>
#include <queue>
#include <sstream>
#include <ctime>
#include <iterator>
#include <string.h>
#include <stack>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <fstream>
#include <assert.h>
#include <numeric>
#include <complex>
#include <random>
#include <utility>



#define IOS ios_base::sync_with_stdio(0),cin.tie(0), cout.tie(0);
#define FOR(i,a,b) for(int i = (a); i < (b); i++)
#define RFOR(i,a,b) for(int i = (a) - 1; i>=(b);i--)
#define rep(i,n) FOR(i,0,n)
#define PB push_back
#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define VI vector<int>
#define PII pair<int,int>
#define PLL pair<long long,long long>
#define VL vector<long long >
#define FILL(a, value) memset(a, value, sizeof(a))
const int nax = 2 * (int)1e5 + 147;
 
using namespace std;
 
const int MOD = 998244353;
const int INF = 1e9 +47 ;
const long long LINF = (long long)1e18 + 4747;
 
typedef long long LL;
const double EPS=1e-6;

int main() {
    int n,k;
    cin >> n >> k;
    string s;
    cin >> s;
    pair<int,int > cur = {0,0};
    if(s[0] =='R') cur = {1,0};
    
    for(int i =(s[0] =='R') ;i < k;i ++) {
        while(true) {

            cur = {cur.first ^ 1, cur.second + 1};

            if(cur.second == n) {
                cout << k - i << '\n';
                return 0;
            }
            if(cur.first == 0 && s[cur.second] == 'R') {
                cur = {cur.first ^ 1, cur.second};
                break;
                
            }
            else if(cur.first == 1 && s[cur.second] =='L') {
                cur = {cur.first^1,cur.second};
                break;
            }

        }
    }
    cout << 0 << '\n';
    
}