A 20-year-old male patient 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 lips red border has hemorrhagic scabs, oral mucosa has large erosions and ulcers merging with each other and covered with greyish-white coating on the background of diffuse hyperemia. Conjunctivitis is observed. The skin of the forearms has erythematous spots sized 1,5 cm in diameter, with blisters in their center. What is the most probable diagnosis?