View Compilation Error

0_0_14827362_19405.cpp:2:11: error: '::main' must return 'int'
 void main()
           ^
0_0_14827362_19405.cpp: In function 'int main()':
0_0_14827362_19405.cpp:5:10: error: 'doublea' was not declared in this scope
          doublea,b,c;
          ^
0_0_14827362_19405.cpp:5:18: error: 'b' was not declared in this scope
          doublea,b,c;
                  ^
0_0_14827362_19405.cpp:5:20: error: 'c' was not declared in this scope
          doublea,b,c;
                    ^
0_0_14827362_19405.cpp:9:22: error: 'a' was not declared in this scope
   scanf("%lf%lf%lf",&a,&b,&c);
                      ^