if(l >= r) return;
int pivot = a[(l + r) / 2];
int i = l, j = r;
while(i <= j){
	while(a[j] > pivot && i <= j){
		--j; ++count;
	}
	while(a[i] < pivot && i <= j){
		++i; ++count;
	}
	if(i <= j){
		std::swap(a[i], a[j]);
		++i; --j;
	}
}
qsortm(l, j);
qsortm(i, r);

}