DETERMINATION OF OPTIMAL TERMS FOR EXECUTION OF RADICAL BARIATRIC INVASIONS AFTER INTRAGASTRIC BALLOONING OF STOMACH THROUGH RESEARCH OF CHANGES IN THICKNESS OF GASTRIC WALL AMONG... oleh I.M. Molnar, O.Y. Yoffe, Y.P. Tsiura, O.M. Kryvoruk, M. S. Kryvopustov