Andy beat me to the wire-OR approach. Here is a variation.
Use 27 small signal diodes (1N914, 1N4148, etc.) and one common pull-down resistor. Depending on the headroom between the lowest high-level input voltage to be detected and the low-high transition voltage of whatever logic family you are using, it might be enough to simply connect the common node to a gate input. What are the lowest input voltage level to be detected, and the power supply voltage(s) available for the input circuit?
This circuit illustrates the concept. It is not complete because many details are not yet supplied by the TS.
The 27 diodes and R1 form a wire-OR gate; when any input goes high, the voltage across R1 increases above the transition level of whatever is acting as a detector.
The nominal transition level for a TTL gate is approx. 1.8 V, which is far enough below the input voltage minus the diode forward voltage drop to be a reliable detection threshold. Note that if the downstream circuit is a bipolar TTL family (74xx, 74LSxx, etc.) the max value for R1 is relatively low.
CMOS families with a "T" in the descriptor (HCT, AC, etc.) also should work directly. Non-T CMOS families (HC, AC, etc.) and most 4000 series gates will not, because the transition level is approx (Vcc / 2), too close to the input signal voltage after a diode.
For a non-5 V input circuit, you'll probably need an analog comparator. The schematic shows the basic form. Missing are the operating voltages, a possible output pull up resistor, possible hysteresis, etc., because application details are not given by the TS.