I didn't get logic for these to lines

1. f |= (ch == '-')
2. x = (x << 1) + (x << 3) + (ch ^ 48);

template<class T>void read(T& x)
{
	x = 0; int f = 0; char ch = getchar();
	while (ch < '0' || ch>'9') { f |= (ch == '-'); ch = getchar(); }
	while (ch >= '0' && ch <= '9') { x = (x << 1) + (x << 3) + (ch ^ 48); ch = getchar(); }
	x = f ? -x : x;
	return;
}