View Compilation Error

0_0_19426864_27053.cpp: In function 'int main()':
0_0_19426864_27053.cpp:28:36: error: 'a' was not declared in this scope
         while (~scanf ("%d %d %d",&a,&b,&c))  
                                    ^
0_0_19426864_27053.cpp:28:39: error: 'b' was not declared in this scope
         while (~scanf ("%d %d %d",&a,&b,&c))  
                                       ^
0_0_19426864_27053.cpp:28:42: error: 'c' was not declared in this scope
         while (~scanf ("%d %d %d",&a,&b,&c))  
                                          ^