ll@t;
rep(t){
	ll@n,@m,@l[n],@r[n];

	ll a=-1,b=m+2;
	while(a+1<b){
		ll c=a+b>>1;
		ll s=0;
		rep(i,n){
			s+=min(max(c,l[i]),r[i]);
		}
		if(s<=m){
			a=c;
		}else{
			b=c;
		}
	}
	if(a<0||a>m){
		wt(-1);
	}else{
		ll s=m;
		rep(i,n){
			s-=min(max(a,l[i]),r[i]);
		}
		ll y=0,z=0;
		rep(i,n){
			ll x=min(max(a,l[i]),r[i]);
			if(s>0&&x<r[i]){
				++x;
			}
			z+=y*x;
			y+=x;
		}
		wt(z);
	}
}