For any two points M and N in the XY-plane, let MN denote the vector from M to N, and 0 denote the zero vector. Let P, Q and R be three distinct points in the XY-plane. Let S be a point inside the triangle ΔPQR such that SP + 5SQ + 6SR = 0. Let E and F be the mid-points of the sides PR and QR, respectively. Then the value of (length of the line segment EF)/(length of the line segment ES) is _______________.