Logic gates question

[walid]

Hi everybody

If i have 4 inputs (logic 1 or 0)
What logic gates must be to light a lamp if only two (any two) of the input is at logic one?
THANKS

[mettula]

well I made the expression using Karnaugh mapps and the resultant expression is quite long because of the nature of the posibilities. hope it helps
mettula

[kumaratea]

    4 input nand gate