#include<bits/stdc++.h> typedef long long ll; #define pb push_back #define mp make_pair #define fi first #define se second using namespace std; ll i,has,mo=1e9; ll com(ll aa) { return (aa*(aa+1)/2)%mo; } int DistanceSum(int N, int *X, int *Y) { for(i=1;i<=N;i++) has=(has+com(i-1)+com(N-i))%mo; return has; }