  In p-p collisions, there are two leading particles. One is in projectile
fragmentation region. The other is in target fragmentation region. The
investigations of present paper show that, just like in nucleus-nucleus
collisions, the revised Landau hydrodynamic model alone is not enough to have a
good description to the measured pseudorapidity distributions of the produced
charged particles in p-p collisions. Only after the leading particles are taken
into account as well, can the experimental data be matched up properly. The
theoretical model works well in p-p collisions in the whole available energy
region from sqrt(s_NN) =23.6 to 900 GeV.
