Four different uniform and constant magnetic fields ${\overrightarrow{B}}_1=B_0\widehat{k},{\overrightarrow{B}}_2=2B_0\widehat{k},{\overrightarrow{B}}_3=3B_0\widehat{k}$ and ${\overrightarrow{B}}_4=4B_0\widehat{k}$ exist in first, second, third and fourth quadrant respectively of x-y plane as shown in figure.  A square wireframe PQRS of one side $\mathcal{l}$ and total resistance R lying in x-y plane is moving with velocity $\overrightarrow{v}=v_0\widehat{i}$ such that its centre lies on x-axis and side PQ is parallel to x-axis. $B_0$ and $V_0$ are positive constants. Then the magnitude of current induced in the square loop at the instant its centre lies of origin is