View Compilation Error

0_0_37510866_5385.cpp: In function 'int main()':
0_0_37510866_5385.cpp:13:17: error: 'a' was not declared in this scope
         cin>>n>>a>>b;
                 ^
0_0_37510866_5385.cpp:13:20: error: 'b' was not declared in this scope
         cin>>n>>a>>b;
                    ^