View Compilation Error

0_0_19766974_9382.cpp: In function 'int main()':
0_0_19766974_9382.cpp:10:17: error: 'a' was not declared in this scope
     scanf("%d",&a);
                 ^
0_0_19766974_9382.cpp:14:18: error: 'a' was not declared in this scope
    printf("%d\n",a);
                  ^