Draw the network for this assignment problem.

Min $10$xiA $+12$x$1$B $+15$xic $+25$xiD $+11$x$2$A $+14$x$2$B $+19$x$2$c $+32$x$2$D

$+18$x$3$A $+21$x$3$B $+23$x$3$c $+29$x$3$D $+15$x$4$A $+20$x$4$B $+26$x$4$c $+28$x$4$D

s$.$t$.$ X$1$A$+$ X$1$B $+$ X$1$C $+$X$1$D $=1$

X$2$A $+$ X$2$B $+$ X$2$C $+$ X$2$D $=1$

X$3$A $+$ X$3$B $+$ X$3$C $+$ X$3$D $=1$

X$4$A $+$ X$4$B $+$X$4$C $+$ X$4$D $=1$

X$1$A $+$ X$2$A $+$X$3$A $+$ X$4$A $=1$

X$1$B $+$ X$2$B $+$X$3$B $+$ X$4$B $=1$

X$1$C $+$ X$2$C $+$ X$3$C$+$ X$4$C $=1$

X$1$D $+$ X$2$D $+$X$3$D $+$X$4$D $=1$