#include<bits/stdc++.h>
using namespace std;
main(){
int k,mx=0;
string s;
cin>>s>>k;
multiset<char>m;
for(int j=0,i=0;s[i]!='\0';i++){
m.insert(s[i]);
while(*m.rbegin()-*m.begin()>k){
m.erase(m.find(s[j]));
j++;
}
mx=max(mx,i-j+1);
}
cout<<mx<<"\n";
}
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