Definition: You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. You are required to assign a label 'formal' if there is an absence of emotion and a presence of questions anywhere within the conversation. If such pattern is not found assign the label 'informal'.
Input:  Person1:       Look , here're two coins named Kai Yuan Tong Bao — the sort of coin made in memory of the founding of a new dynasty . These two coins were made in different periods of the Tang Dynasty .  
 Person2:How can you tell the difference ? From what I see , they look almost the same .  
 Person1:        The one made in the early Tang period is bigger and has more characters on it , while the one with smaller and elegant characters was made in late Tang period . Look carefully , and tell me if you see the difference now .  
 Person2:Yes , they are different ! But it's too professional . What I need is just being able to tell the real from the fake . Do you know any method we can use to tell a fake ancient coin ?  
 Person1:        Various methods were used in history to produce fake coins . We usually send the coin to an authorized unit to have it tested by experts with special machines . We can judge it with naked eyes .  
 Person2:I see . By the way , China was more than once ruled by foreign tribes in history . Did they issue their own coins in China ?  
 Person1:        Certainly , they did . Liao Coins and Song Coins , for example , coexisted in circulation during the Southern Song and Yuan period some 800 -1000 years ago . The Liao Coins look plain and bold in style , just like the characteristics of the Mongolian tribe . Let me look for one and show you .  
 Person2:If you happen to find one , please bargain with the owner for it . I'd like to have one . It's interesting to see the integration of the Han and Mongolian cultures on this small piece of metal . 

formal