Then you can do two lines solution (read the data, print (calculation(x, y, n) ) )
I can not proof solution too, but you get AC and this isn’t indirect proof that your solution is right?
Always we can do:
read x, y, n,
sol1 = bla + bla + bla
sol2 = abla * abla
soln = 4*n;
print (min(sol1, sol2,…soln))
but if calculation is much time costly, we can get TLE
Then [if is tle problem] we can send sol1, sol2 … separetly, one by one:
.red x, y, n
print (sol1(x, y, n))
read x, y, n
print (sol2(abla, abla))
If you want proof, good picture is essential --> pen and checkere paper or graphic draw program, for example geogebra, autocad, inkscape, 3d modeler [blender] etc.