A 20-year-old man complains of sharp pain in the mouth, increase of body temeperature up to 38,5°C, headache and aching joints, general weakness. The disease onset was 3 days ago due to overexposure to cold. Objectively: the red border is covered with hemorrhagic scabs, oral mucosa has large erosions and ulcers merging with each other and covered with grayish-white coating against the background of diffuse hyperemia. Conjunctivitis is observed. The skin of the forearms has erythematous spots 1,5 cm in diameter, with blisters in their center. What is the most likely diagnosis?