View Compilation Error

0_0_18756218_4438.cpp: In function 'int main()':
0_0_18756218_4438.cpp:14:3: error: 'ax' was not declared in this scope
   ax.clear();
   ^
0_0_18756218_4438.cpp:15:3: error: 'ay' was not declared in this scope
   ay.clear();
   ^