Probability density function for acquiring at least one Wolf-Rayet star (solid curves) or at least one star sufficiently massive to experience a supernova (dotted curves) from the adopted broken power-law initial mass function. The red curves give the probabilities when we adopt a single fixed upper limit of 120 M_⊙ to the initial mass function. For this mass function, even a very low-mass cluster could still host, by chance, a Wolf-Rayet star or a star sufficiently massive to experience a supernova explosion. The blue curve gives the probabilities of finding a massive star for a mass function with a variable upper mass limit according to Eq. (2). For the latter mass function a cluster should contain at least ∼200 stars to host a star sufficiently massive to experience a supernova, and at least ∼900 stars before it can host a Wolf-Rayet star.