+(+(+(+(y,y),+(c0,y)),+(c0,+(c0,c0))),c0) = +(z,+(+(+(y,c0),+(y,y)),+(+(c0,x),c0)))
+(+(x,+(+(y,y),+(c0,c0))),+(+(c0,+(c0,c0)),c0)) = z
c0 = z