B - Wet Shark and Bishops.cpp

/*
RAJAT SINGH
VIT VELLORE
*/
 
#include<bits/stdc++.h>
using namespace std;
#define ll   long long 
//#define max 706000
#define gc getchar_unlocked
#define pc putchar_unlocked
//inline void get(int *p){register  int n=0,sign=1,a=gc();while(a<'0'||a>'9'){ if(a=='-'){sign=-1;a=gc();break;} a=gc();}while(a>='0' && a<='9'){n=(n<<1)+(n<<3)+a-'0';a=gc();}*p=n*sign;}
  
 
//inline void put(int n){char d[10];int i=0;if(n<0){pc('-');n=-n;}do{d[i++]=n%10+'0';n=n/10;}while(n);while(i)pc(d[--i]);pc('\n');}
#define     sc(a)  scanf("%lld",&a) 
#define     p(a)  printf("%lld\n",a) 
#define     l(i,a)  for(i=0;i<a;i++)
#define     re(j,a,b)  for(j=a;j<=b;j++)  
# define ll   long long 
#define modu 1000000007
int modular_pow(ll int  base, ll int  exponent,int m)
{
    if(exponent==0)
    return 1;
    else if(exponent%2==0){
        ll int res=modular_pow(base,exponent/2,m);
        return (res*res +m)%m;
        
        
    }
    else{
        return (modular_pow(base,exponent-1,m) * base)%m;
        
    }
}
 
 
 
 int gcd(int a,int b){
    if(b==0)
    return a;//gcd
    else return gcd(b,a%b);
 }
 
bool chek(int x){
    return (x&&!(x&(x-1)));// power of 2
}
int onebits(int n){
    return __builtin_popcount(n);//count number od set bits in a number
 
}
 
 
/*
finaaly it worked!!!!!!
 
*/

 int main(){
//freopen("input.txt","r",stdin);
int t;
cin>>t;
map< ll , ll >m;
map< ll , ll >m1;
while(t--){
	ll int x,y;
	cin>>x>>y;
         m[x+y]++;
      //   if(x>=y)
         m1[x-y]++;
        // else m[y-x]++;
	
}
ll int ans=0;
for(map< ll , ll >::iterator i=m.begin();i!=m.end();i++){
	if(i->second>1){
		ll int k=i->second;
		ll int uu=k*(k-1);
		uu/=2;
		ans+=uu;
		//ans+=((i->second*(i->second-1))/2);
		
	}
//	cout<<i->first<<" "<<i->second<<endl;
	
}
for(map< ll , ll >::iterator i=m1.begin();i!=m1.end();i++){
	if(i->second>1){
		ll int k=i->second;
		ll int uu=k*(k-1);
		uu/=2;
		ans+=uu;
		//ans+=((i->second*(i->second-1))/2);
		
	}
//	cout<<i->first<<" "<<i->second<<endl;
	
}
cout<<ans<<endl;
m.clear();
return 0;}