#include<bits/stdc++.h>
using namespace std;

int main(){
  int N, X;
  char S;
  int cnt;

  cin>>N>>X;
  cnt = X;
  
  for (int i=0; i<N; i++){
    cin>>S;
    if (S == 'o') cnt += 1;
    else{
      if (cnt>0) cnt -= 1;
    }
  }
  cout << cnt << endl;
}

#include<iostream>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<cmath>
#include<map>
#include<string>
#include<bitset>

using namespace std;

#define rep(i,N) for(ll i=0;i<N;i++) //0から


typedef long long ll;




ll binary_search(vector<ll> a, ll n, ll key){
    ll right = n, left = -1;
    ll md = (right + left) / 2;

    while(right - left > 1){
        if(a[md] <= key){
            right = md;
        }else{
            left = md;
        }
        md = (right + left) / 2;
    }
    if(left == -1) return -1; //無い場合
    return right;
}

vector<ll> prime;
void Prime(ll n){ //線形篩,素数列挙
    vector<ll> p(n,0);
    p[0]=1;
    p[1]=1;
    for(ll i=2;i<n;i++){
        if(p[i]==0){
            prime.push_back(i);
            p[i]=i;
        }
        ll k=prime.size();
        for(ll j=0;j<k && i*prime[j]<n && prime[j]<=p[i];j++){
            p[i*prime[j]]=prime[j];
        }
    }
}

ll gcd(ll a,ll b){
    if(a<b){
        swap(a,b);
    }
    //a>=b
    ll r=a%b;
    while(r!=0){
        a=b;
        b=r;
        r=a%b;
    }
    return b;
}

ll modexp(ll x, ll a, ll m){ //x^a mod m
    ll ret = 1;
    while (a > 0) {
        if (a & 1) ret = ret * x % m;  // n の最下位bitが 1 ならば x^(2^i) をかける
        x = x * x % m;
        a >>= 1;  // n を1bit 左にずらす
    }
    return ret;
}

ll modinv(ll a, ll m){ //a^{-1} mod m
    ll b=m,u=1,v=0;
    while(b){
        ll t=a/b;
        a-=t*b; swap(a,b);
        u-=t*v; swap(u,v);
    }
    u=(u+m)%m;
    return u;
}


ll nCr(ll n, ll r) {
    r = min(r, n-r);
    ll ans = 1;
    for (ll i = n; i > n - r; --i) {
        ans = ans*i;
    }
    for (ll i = 1 ; i < r + 1; ++i) {
        ans = ans / i;
    }
    return ans;
}

double pi=3.14159265358979323846;


//next_purmitation!!!!!!!!!!!!!
//https://atcoder.jp/contests/abc198/tasks/abc198_d
//cout<<fixed<<setprecision(18);
int main(){
    ll n;
    cin>>n;
    ll ans=1;
    for(ll i=1;i<=11;i++){
        ans*=n-i;
        ans/=i;
    }
    cout<<ans<<endl;

    return 0;
}