View Compilation Error

0_0_35646805_3732.cpp: In function 'int main()':
0_0_35646805_3732.cpp:3:18: error: 'a' was not declared in this scope
    scanf("%d%d",&a,&b);
                  ^
0_0_35646805_3732.cpp:3:21: error: 'b' was not declared in this scope
    scanf("%d%d",&a,&b);
                     ^