#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define pb emplace_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}
vi seg;
ll N;
void init(ll n){
    N=1;
    while(N<n)N*=2;
    seg=vi(N*2-1);
}
void add(ll i,ll x){
    i=N+i-1;
    seg[i]+=x;
    while(i>0){
        i=(i-1)/2;
        seg[i]=seg[i*2+1]+seg[i*2+2];
    }
}
ll getsum(ll a,ll b,ll k,ll l,ll r){
    if(r<=a||b<=l)return 0;
    if(a<=l&&r<=b)return seg[k];
    ll c1=getsum(a,b,k*2+1,l,(l+r)/2);
    ll c2=getsum(a,b,k*2+2,(l+r)/2,r);
    return c1+c2;
}
inline ll readll() {
    ll x = 0;
    char ch = getchar_unlocked();
    while (ch < '0' || ch > '9') ch = getchar_unlocked();
    while (ch >= '0' && ch <= '9'){
		x = (x << 3) + (x << 1) + ch - '0';
		ch = getchar_unlocked();
	}
    return x;
}
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n;cin>>n;
    vp v(n);
    rep(i,n){
        ll a,b;cin>>a>>b;
        v[i].fi=a+b;v[i].se=a-b;
    }sort(all(v));
    vi srt(n);rep(i,n)srt[i]=v[i].se;sort(all(srt));
    init(n);
    ll ans=0;
    rep(i,n){
        ll l=lb(srt,v[i].se);
        ans+=getsum(0,l+1,0,0,N);
        add(l,1);
    }
    out(ans);
}
#pragma GCC optimize("Ofast")

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vi vector<int>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define pb push_back

bool solve()
{
    int n;
    cin >> n;
    vi x(n);
    vi y(n);
    rep(i,n){
        cin >> x[i] >> y[i];
    }

    int ans = 0;
    for(int i = 0; i < n-1; i++){
        for(int j = i+1; j < n; j++){
            if(abs(y[i]-y[j]) <= abs(x[i]-x[j])){
                ans++;
            }
        }
    }

    cout << ans << endl;

    return true;
}

int main()
{
    solve();
    return 0;
}