Let ABCD be a quadrilateral. If E and F are the mid points of the diagonals AC and BD respectively and (AB⃗−BC⃗)+(AD⃗−DC⃗)=kFE⃗ (\vec{AB}-\vec{BC})+(\vec{AD}-\vec{DC})=k \vec{FE} (AB−BC)+(AD−DC)=kFE, then k is equal to