View Compilation Error

0_0_27684449_16785.c: In function 'main':
0_0_27684449_16785.c:62:3: error: 'wall' undeclared (first use in this function)
   wall = 0;
   ^
0_0_27684449_16785.c:62:3: note: each undeclared identifier is reported only once for each function it appears in