I've been thinking about nuclear fusion process in the sun, and stumbled upon something weird: Basically, why there is a net energy from PP fusion? We have an input of 4 protons and output of 2 protons and 2 neutrons, now, a mass of a neutron is slightly larger than a mass of proton, so the result appears to be more massive, than the input! Some online research shown that it doesn't go just that simple, but the PP-chain process have the same problem - the input is 6 protons, the output is 2 neutrons and 4 protons, which is again more massive than the input, and above that there are 2 positrons, neutrinos and gamma-quants of net output. Where does the energy come from? Kinetic energy of proton collisions? If yes, what is the point of fusion, if it only reemit parts of the heat that make it go in the first place? Something does not add up, where am i wrong?