View Compilation Error

0_0_37056651_27503.cpp: In function 'int main()':
0_0_37056651_27503.cpp:15:24: error: 'a' was not declared in this scope
         scanf("%d %d",&a,&b);
                        ^
0_0_37056651_27503.cpp:15:27: error: 'b' was not declared in this scope
         scanf("%d %d",&a,&b);
                           ^