Today was an ordinary day. You were walking home from school and listening to the sound of autumn crunching leaves under your feet, humming a song with your lips, when suddenly... You saw a young man lying on the ground and writhing in pain. You quickly approached him and noticed a knife wound in his stomach, it seems he was stabbed by a man who was walking not far from this street, walking quickly in black clothes and a mask, hiding his face. What will you do?