ll@n,@m,u[m],v[];
rep(i,m){
	ll@x,@y;
	u[i]=x+y-1;
	v[i]=x-y;
}
ll c=0;
int mu=m;
Unique(mu,u);
int mv=m;
Unique(mv,v);
rep(j,mv) c+=n-abs(v[j]);
ll mc=bsearch_min[ll,j,0,mv](v[j]>=0);
if(1){
	ll j=mc-1,k=mc;
	ll a[2]{0,0};
	rep(i,mu){
		ll un=u[i];
		if(un>=n) break;
		c+=un;
		while(j>=0&&un+v[j]>0) ++a[v[j]&1],--j;
		while(k<mv&&un-v[k]>0) ++a[v[k]&1],++k;
		c-=a[un&1^1];
	}
}
if(1){
	ll j=mc-1,k=mc;
	ll a[2]{0,0};
	rrep(i,mu){
		ll un=2n-u[i];
		if(un>n) break;
		c+=un;
		while(j>=0&&un+v[j]>0) ++a[v[j]&1],--j;
		while(k<mv&&un-v[k]>0) ++a[v[k]&1],++k;
		c-=a[un&1^1];
	}
}
wt(c);