View Compilation Error

0_0_22932085_30459.cpp: In function 'int main()':
0_0_22932085_30459.cpp:6:12: error: 'n' was not declared in this scope
  int s,i,a[n];
            ^
0_0_22932085_30459.cpp:12:18: error: 'a' was not declared in this scope
      scanf("%d",&a[n]);
                  ^
0_0_22932085_30459.cpp:13:11: error: 'a' was not declared in this scope
      sort(a,a+n);
           ^
0_0_22932085_30459.cpp:13:16: error: 'sort' was not declared in this scope
      sort(a,a+n);
                ^