/in/foo.cc: In function 'int main()':
/in/foo.cc:4:18: error: 'a' was not declared in this scope
   scanf("%d%d", &a, &b);
                  ^
/in/foo.cc:4:22: error: 'b' was not declared in this scope
   scanf("%d%d", &a, &b);
                      ^