View Compilation Error

0_0_21768056_10192.cpp: In function 'int main()':
0_0_21768056_10192.cpp:4:7: error: 'a' was not declared in this scope
  cin>>a>>b;
       ^
0_0_21768056_10192.cpp:4:10: error: 'b' was not declared in this scope
  cin>>a>>b;
          ^