The total number of species from the following in which one unpaired electron is present, is _______. \( \text{N}_2, \text{O}_2, \text{C}_2^{-}, \text{O}_2^{-}, \text{O}_2^{2-}, \text{H}_2^{+}, \text{CN}^{-}, \text{He}_2^{+} \)