import java.util.*;
class Main{
public static void main
(String[] args
) { int n=4;
int [] arr={1,3,5,6};
int i=0;
int k=2;
int count=0;
for(int j=0;j<n;j++){
while(arr[j]-arr[i]>k){
i++;
}
count+=j-i;
}
}
}
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