A sample of hydrogen atoms containing all the atoms in a particular excited state absorb radiations of a particular wavelength by which  the atoms get excited to another excited state. When the atoms finally de-excited to the ground state, they emit the radiations of 10 different wavelengths. Out of these 10 radiations, 7 have wavelengths shorter than the absorbed radiation and 2 have wavelength longer than the absorbed radiation. The orbit number for the initial excited state of atoms is