View Compilation Error

0_0_29100943_22861.cpp: In function 'int main()':
0_0_29100943_22861.cpp:8:21: error: 'n' was not declared in this scope
         scanf("%d",&n);
                     ^
0_0_29100943_22861.cpp:9:48: error: 'a' was not declared in this scope
         for (int i = 1;i <= n;i++) scanf("%d",&a[i]);
                                                ^
0_0_29100943_22861.cpp:10:14: error: 'a' was not declared in this scope
         sort(a+1,a+n+1);
              ^