View Compilation Error

0_0_27461387_19411.cpp: In function 'int main()':
0_0_27461387_19411.cpp:3:19: error: 'a' was not declared in this scope
     scanf("%d%d",&a,&b);
                   ^
0_0_27461387_19411.cpp:3:22: error: 'b' was not declared in this scope
     scanf("%d%d",&a,&b);
                      ^