#include<bits/stdc++.h>
using namespace std;
long long int ar[200009];
int m;
int maxm=0;
int bs(int n){
int mid;
int l,r;
int ans =m;
l=0,r=m-1;
int key=0;
while (l<=r){
mid = (l+r)/2;
if(n == ar[mid]){
ans = mid;
l = mid+1;
}
if(n>ar[mid]) {
l=mid+1;
}
else if(n<ar[mid]){
ans = mid;
r=mid-1;
}
}
return ans;
}
int main()
{
cin>>m;
for(int i=0;i<m;i++){
cin>>ar[i];
}
sort(ar,ar+m);
for(int i=0;i<m;i++){
int ans1= bs(ar[i]+5);
if(ar[i]+5 == ar[ans1]){
//cout<<"yes"<<endl;
maxm=max(maxm,(ans1-i+1));
}
else{
maxm=max(maxm,(ans1-i));
}
}
cout<<maxm<<endl;
return 0;
}
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100
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