View Compilation Error

0_0_20970314_10614.cpp: In function 'int main()':
0_0_20970314_10614.cpp:15:29: error: 'scanf' was not declared in this scope
     while(scanf("%d%d",&n,&m)!=EOF)
                             ^
0_0_20970314_10614.cpp:15:32: error: 'EOF' was not declared in this scope
     while(scanf("%d%d",&n,&m)!=EOF)
                                ^
0_0_20970314_10614.cpp:19:25: error: 'read' was not declared in this scope
             a[i].x=read();
                         ^
0_0_20970314_10614.cpp:23:23: error: 'sort' was not declared in this scope
         sort(a,a+n,cmp);
                       ^
0_0_20970314_10614.cpp:39:22: error: 'read' was not declared in this scope
             lll=read();
                      ^
0_0_20970314_10614.cpp:61:29: error: 'printf' was not declared in this scope
            printf("%d\n",ans);
                             ^