View Compilation Error

838654_0_0_6422.c: In function `main':
838654_0_0_6422.c:6: error: `y1' undeclared (first use in this function)
838654_0_0_6422.c:6: error: (Each undeclared identifier is reported only once
838654_0_0_6422.c:6: error: for each function it appears in.)
838654_0_0_6422.c: At top level:
838654_0_0_6422.c:10: error: syntax error before "return"