test

#pragma comment(linker, "/STACK:102400000,102400000")
#include <math.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <set>
#include <map>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <bitset>
#include <iostream>
#include <algorithm>
#define pb push_back
#define fi first
#define se second
#define icc(x) (1<<(x))
#define lcc(x) (1ll<<(x))
#define lowbit(x) (x&-x)
#define debug(x) cout<<#x<<"="<<x<<endl
#define rep(i,s,t) for(int i=s;i<t;++i)
#define per(i,s,t) for(int i=t-1;i>=s;--i)
#define mset(g, x) memset(g, x, sizeof(g))
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;
typedef double db;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> veci;
const int mod=(int)1e9+7,inf=0x3fffffff,rx[]={-1,0,1,0},ry[]={0,1,0,-1};
const ll INF=1ll<<60;
const db pi=acos(-1),eps=1e-8;

template<class T> void rd(T &res){
    res = 0; int ch,sign=0;
    while( (ch=getchar())!='-' && !(ch>='0'&&ch<='9'));
    if(ch == '-') sign = 1; else res = ch-'0';
    while((ch=getchar())>='0'&&ch<='9') res = (res<<3)+(res<<1)+ch-'0';
    res = sign?-res:res;
}
template<class T>void rec_pt(T x){
    if(!x)return;
    rec_pt(x/10);
    putchar(x%10^48);
}
template<class T>void pt(T x){
    if(x<0) putchar('-'),x=-x;
    if(!x)putchar('0');
    else rec_pt(x);
}
template<class T>inline void ptn(T x){ pt(x),putchar('
'); }
template<class T>inline void Max(T &a,T b){ if(b>a)a=b; }
template<class T>inline void Min(T &a,T b){ if(b<a)a=b; }
template<class T>inline T mgcd(T b,T d){ return b?mgcd(d%b,b):d; }//gcd模板，传入的参数必须是用一类型
//-------------------------------主代码--------------------------------------//

map<pair<ll, int>, int> mmp;

int main()
{
    int n;
    cin >> n;
    while (n --) {
        int x,y;
        cin >> x >> y;
        // ->
        pair<ll, int> tmp;
        tmp.first = x;
        tmp.second = 0;
        mmp[tmp]++;
        // 1
        if (y > x) {
            tmp.first = -(y - x);
        } else {
            tmp.first = x - y;
        }
        tmp.second = 1;
        mmp[tmp]++;
        //2
        tmp.first = y;
        tmp.second = 2;
        mmp[tmp]++;
        //3
        tmp.first = x + y;
        tmp.second = 3;
        mmp[tmp]++;
    }
    
    ll ans = 0;
    map<pair<ll, int>, int>::iterator p;
    for (p = mmp.begin(); p != mmp.end(); p++) {
        ll _value = (*p).second;
        pair<ll, int>_tmp = (*p).first;
        ans += _value * (_value - 1) /2;
    }
    cout << ans;
    return 0;
}


#ifdef CJS_DEBUG
/**************/

5
1 1
2 2
3 3
1 3
3 1

/***********/
#endif