View Compilation Error

0_0_38994620_23636.c: In function 'main':
0_0_38994620_23636.c:38:16: error: 'a' undeclared (first use in this function)
   38 |         memset(a,-1, sizeof(a));
      |                ^
0_0_38994620_23636.c:38:16: note: each undeclared identifier is reported only once for each function it appears in