View Compilation Error

210257_0_18947.c: In function `main':
210257_0_18947.c:30: error: `stu' undeclared (first use in this function)
210257_0_18947.c:30: error: (Each undeclared identifier is reported only once
210257_0_18947.c:30: error: for each function it appears in.)
210257_0_18947.c:31: error: `classpj' undeclared (first use in this function)
210257_0_18947.c:32: error: `st' undeclared (first use in this function)