View Compilation Error

0_0_18119793_19822.cpp: In function 'int main()':
0_0_18119793_19822.cpp:4:17: error: 'a' was not declared in this scope
     while (cin>>a>>b)cout<<a+b<<endl;
                 ^
0_0_18119793_19822.cpp:4:20: error: 'b' was not declared in this scope
     while (cin>>a>>b)cout<<a+b<<endl;
                    ^