| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simpr |  | 
						
							| 2 |  | f1ofn |  | 
						
							| 3 |  | difss |  | 
						
							| 4 |  | dmss |  | 
						
							| 5 | 3 4 | ax-mp |  | 
						
							| 6 |  | f1odm |  | 
						
							| 7 | 5 6 | sseqtrid |  | 
						
							| 8 | 7 | sselda |  | 
						
							| 9 |  | fnelnfp |  | 
						
							| 10 | 2 8 9 | syl2an2r |  | 
						
							| 11 | 1 10 | mpbid |  | 
						
							| 12 |  | f1of1 |  | 
						
							| 13 | 12 | adantr |  | 
						
							| 14 |  | f1of |  | 
						
							| 15 | 14 | adantr |  | 
						
							| 16 | 15 8 | ffvelcdmd |  | 
						
							| 17 |  | f1fveq |  | 
						
							| 18 | 13 16 8 17 | syl12anc |  | 
						
							| 19 | 18 | necon3bid |  | 
						
							| 20 | 11 19 | mpbird |  | 
						
							| 21 |  | fnelnfp |  | 
						
							| 22 | 2 16 21 | syl2an2r |  | 
						
							| 23 | 20 22 | mpbird |  | 
						
							| 24 |  | eldifsn |  | 
						
							| 25 | 23 11 24 | sylanbrc |  |