what is the max freq i pic can measure through a PIC input

Sorry for hi-jack, but since we're on frequency, what is the max freq i pic can measure through an input?

Back a couple of decades, MicroChip published an application note for a 50MHz frequency counter using an OTP chip (it was before EEPROM devices) and 7 segment LED displays. There have been numerous individual improvements to this, using more modern EEPROM chips and LCD displays.

Note this is a guaranteed 50MHz, in practice individual chips will probably exceed this.