$ \text{Let the focal chord of the parabola } P: y^{2}=4x \text{ along the line } L: y=mx+c,; m>0 \text{ meet the parabola at the points } M \text{ and } N. \text{ Let the line } L \text{ be a tangent to the hyperbola } H: x^{2}-y^{2}=4. \text{ If } O \text{ is the vertex of } P \text{ and } F \text{ is the focus of } H \text{ on the positive } x\text{-axis, then the area of the quadrilateral } OMFN \text{ is:} $