View Compilation Error

0_0_4441294_13886.c: In function `insert':
0_0_4441294_13886.c:15: error: `heap' undeclared (first use in this function)
0_0_4441294_13886.c:15: error: (Each undeclared identifier is reported only once
0_0_4441294_13886.c:15: error: for each function it appears in.)
0_0_4441294_13886.c: In function `extract':
0_0_4441294_13886.c:25: error: `heap' undeclared (first use in this function)
0_0_4441294_13886.c: In function `main':
0_0_4441294_13886.c:51: error: `MAXN' undeclared (first use in this function)