A man in grave condition was delivered to the admission ward of a hospital on the 2nd day of illness. Examination revealed body temperature of 36,1°C, sharpened features of face, dry skin that makes a fold, aphonia, convulsive twitching of some muscle groups. Acrocyanosis is present. Heart sounds are muffled, Ps is 102 bpm, AP is 50/20 mm Hg. Abdomen is soft, drawn-in, painless. Anuria is presnt. Stool is liquid in form of rice water. What is the most probable diagnosis?