Convert from two's complement to sign-magnitude

So I manage to figure out most of bits.c questions,

however I am struggling with this one and everything I turn out to be false.

/*
 * twosComp2SignMag - Convert from two's complement to sign-magnitude
 *   where the MSB is the sign bit
 *   You can assume that x > TMin
 *   Example: twosComp2SignMag(-5) = 0x80000005.
 *   Legal ops: ! ~ & ^ | + << >>
 *   Max ops: 15
 *   Rating: 4
 */
int twosComp2SignMag(int x) {
  return 2;
}