View Compilation Error

0_0_21973840_16693.cpp: In function 'int main()':
0_0_21973840_16693.cpp:12:3: error: 'b' was not declared in this scope
   b.clear();
   ^
0_0_21973840_16693.cpp:33:23: error: 'n' was not declared in this scope
   for (int i = 0; i < n; i++)
                       ^