A 30-year-old patient has been hospitalized. The patient's history states that the disease onset was acute and started with frequent watery stools, later followed by thirst and profuse vomiting without nausea. Objectively, the body temperature is 35.4°C. The patient's condition is severe, the skin is cold. Tissue turgor and skin elasticity are significantly reduced. The facial features are drawn. The voice is hoarse. Acrocyanosis and anuria are observed. Pulse - 130/min, weak. Blood pressure - 60/30 mm Hg. The tongue is dry. The abdomen is sunken and painless, palpation detects noticeable rumbling in the intestines. What is the most likely diagnosis in this case?