A cain with pendant problem - help please

Problem. A chain is taken (absolute flexible and inextensible thread) of length S and with a specific (linear) mass mc. The chain is suspended at the same height from two ends. The horizontal distance between suspension points is L. A pendant (material point) of mass M is strung on a chain, which can slide along the chain without friction. What will be equal to the arrow of the sag of the pendant?

I solved the problem numerically. Is there an analytical solution?