Safest is to refer to a Solid to Process Pantone swatchbook, but barring that, Photoshop will tell you the closest PMS swatch.
Double click the foreground color swatch to bring up the color picker and enter your CMYK values, but don’t click OK.
Click the custom button.
Switch the pulldown to whatever swatchbook you need (probably one of the Pantone Solids – coated and uncoated refers to the kind of paper the ink will be going on).
See which swatch is highlighted – that’s the closest to your CMYK value.
For Solid Coated, I’m getting 343 for the green and 107 for the yellow.