Top: Respective contributions of gas accretion and collisions to the total mass gain of the 1000 M_⊙ target for different gas accretion rates in the Monte Carlo simulations (mean values). Bottom: Respective contributions of winds and collision-induced mass loss to the total mass lost for the same simulations. The time above the bars shows the mean time to the end of the simulations, and the mean number of collisions is displayed in the corresponding bar chart.