View Compilation Error

0_0_20594691_19798.cpp: In function 'int main()':
0_0_20594691_19798.cpp:10:18: error: 'scanf' was not declared in this scope
     scanf("%d",&t);
                  ^
0_0_20594691_19798.cpp:21:27: error: 'sort' was not declared in this scope
         sort(p+1,p+1+n,cmp);
                           ^
0_0_20594691_19798.cpp:23:33: error: 'abs' was not declared in this scope
             ans += abs(p[i].id-i);
                                 ^
0_0_20594691_19798.cpp:25:43: error: 'printf' was not declared in this scope
         printf("Case #%d: %d\n",ca++,ans/2);
                                           ^