View Compilation Error

0_0_39633913_28828.cpp: In function 'int main()':
0_0_39633913_28828.cpp:11:14: error: 'a' was not declared in this scope
   11 |      cout << a+b << endl;
      |              ^
0_0_39633913_28828.cpp:11:16: error: 'b' was not declared in this scope
   11 |      cout << a+b << endl;
      |                ^