N-body evolution of the semimajor axis, a, of the super-Earths in the compact system Kepler-402 as a function of time, t. The values of a of the planets are initialized to their current (observed) value. The solid curves indicate the semimajor axes. The envelopes are the periapses and apoapses of the orbits. Upon instability, planet b merges with planet c and planet d merges with planet e by giant impacts. No planet becomes metal rich in this simulation, but a different outcome is possible for different initial eccentricities and mean longitudes.