:lol:
Is recommended to put every unused input at Vdd or Vss function by circuit need or function by easy pcb connection.
In case of a real TTL the open inputs is consider in logic "1" state, but the open input is very sensitive to noise and can be easy switch to "0" by this noise.
In case of all CMOS families the open input is in unknown state and can damage the IC if a high supply voltage is used.
So, any unused input must be connected at Vdd or Vss directly or through a resistor, for minimize the hazard.