A circuit is required in order to control a network of switches. The circuit has four inputs: three of the switches are normal on/off switches while the fourth switch is an enable switch for the entire circuit. The circuit should have the following characteristics:
• If the enable switch is off, the single output will be LOW
• Otherwise, if any two (and only two) switches are one, then the output is HIGH
• Three switches will never be on simultaneously
• The circuit output is low under all other conditions