What key details about sergey rusin can be extracted from the following bio? Bio: sergey rusin -lrb- ; born 31 october 1959 -rrb- is a former freestyle swimmer from the soviet union . he competed at the 1980 summer olympics in moscow , ussr , and is best known for winning the gold medal in the men 's 400 m freestyle at the 1977 european championships in sweden .
A:
- medaltemplates is men 's swimming- birth date is 31 october 1959