What was the concentration of the original sample?? please Help!!?

A forensic chemist tests a water sample for cyanide. To do so, the sample is diluted by pipetting 1 mL into an empty 100 mL volumetric flask, which is then filled to the mark with deionized water. If the measured concentration was found to be 0.396 mg/L, what was the concentration of the original sample. (answer in ppm.)