A 53 year old male who is a heavy alcoholic presents with 12 hour history of sharp central abdominal pain and vomiting. He prefers to sit up rather than lying fiat as pain increases on lying down. O/E he has mild jaundice. Temp - 38. 3deg C. Pulse 132/min BP 118/82 mm Hg. There is periumbilical discoloration and maximum tenderness in epigastrium. Diagnosis