View Compilation Error

559510_0_0_9894.c:6: error: syntax error before "node"
559510_0_0_9894.c: In function `main':
559510_0_0_9894.c:13: error: `top' undeclared (first use in this function)
559510_0_0_9894.c:13: error: (Each undeclared identifier is reported only once
559510_0_0_9894.c:13: error: for each function it appears in.)
559510_0_0_9894.c:13: error: `p' undeclared (first use in this function)
559510_0_0_9894.c:13: error: `q' undeclared (first use in this function)
559510_0_0_9894.c:13: error: `r' undeclared (first use in this function)