During a party, a total of 78 handshakes occurred. If each person shook hands once with each of the other people, how many people were at the party?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
During a party, a total of 78 handshakes occurred. If each person shook hands once with each of the other people, how many people were at the party?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
13
During a party, a total of 78 handshakes occurred. If each person shook hands once with each of the other people, how many people were at the party?
train