View Compilation Error

0_0_15451240_11196.c: In function 'main':
0_0_15451240_11196.c:7:13: error: 'r4' undeclared (first use in this function)
     s=a*r*r*r4/3;
             ^
0_0_15451240_11196.c:7:13: note: each undeclared identifier is reported only once for each function it appears in