#include <map>

#include <set>

#include <cmath>

#include <ctime>

#include <stack>

#include <queue>

#include <cstdio>

#include <cctype>

#include <bitset>

#include <string>

#include <vector>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <functional>

#define PI acos(-1)

#define eps 1e-8

#define fuck(x) cout<<#x<<" = "<<x<<endl;

#define lson l,mid,rt<<1

#define rson mid+1,r,rt<<1|1

#define FIN freopen("input.txt","r",stdin);

#define FOUT freopen("output.txt","w+",stdout);

//#pragma comment(linker, "/STACK:102400000,102400000")

using namespace std;

typedef long long LL;

typedef unsigned long long ull;

typedef pair<int, int> PII;

const int maxn = 3e5 + ;

const LL INF = 1e18 + ;

const LL mod = 1e9 + ;

LL gcd(LL a, LL b) {return b ? gcd(b, a % b) : a;}

LL lcm(LL a, LL b) {return a / gcd(a, b) * b;}

LL powmod(LL a, LL b, LL MOD) {LL ans = ; while (b) {if (b % )ans = ans * a % MOD; a = a * a % MOD; b /= ;} return ans;}

double dpow(double a, LL b) {double ans = 1.0; while (b) {if (b % )ans = ans * a; a = a * a; b /= ;} return ans;}

int n, m;

char str[];

int dp[][];

int main() {

#ifndef ONLINE_JUDGE

    FIN

#endif

    scanf("%d%d%s", &n, &m, str + );

    memset(dp, 0x3f3f3f3f, sizeof(dp));

    dp[][] = ;

    //dp[j][k]表示在第i天之前工作j天，并且已经连续工作k天的情况下的最小体力花费

    for (int i = ; i <= n; i++) {

        for (int j = i; j >= ; j--) {

            for (int k = j; k >= ; k--) {

                dp[j][] = min(dp[j][], dp[j][k]);

                if (str[i] == '') {

                    dp[j][k] = min(dp[j][k], dp[j - ][k - ] + k);

                }

            }

        }

    }

    int ans = ;

    for (int i = ; i <= n; i++) {

        for (int j = ; j <= n; j++) {

            if (dp[i][j] <= m) {

                ans = i;

            }

        }

    }

    cout << ans << endl;

}