codeforce - vasya and strings

#include<bits/stdc++.h>
using namespace std;
int n,m;
string s;
typedef long long ll;
ll func(char x)
{
    ll ans=0,i=0,j=0,cnt=0;
    for(i=0; i<n; i++)
    {
        if(s[i]==x)cnt++;
        if(cnt>m)
        {
            while(cnt>m)
            {
                if(s[j++]==x)
                    cnt--;
            }
        }
        ans=max(ans,i-j+1);

    }
    return ans;
}
int main()
{
    cin>>n>>m;
    cin>>s;
    ll a,b;
    a=func('a');
    b=func('b');
    a=max(a,b);
    cout<<a<<endl;
    return 0;
}