View Compilation Error

0_0_34471038_16687.cpp: In function 'int main()':
0_0_34471038_16687.cpp:5:27: error: 'r' was not declared in this scope
     while(scanf("%d%d%d",&r,&v1,&v2)!=EOF){
                           ^
0_0_34471038_16687.cpp:8:13: error: 'PI' was not declared in this scope
         t2=(PI*R)/v2;
             ^