View Compilation Error

0_0_17737552_18493.cpp: In function 'int main()':
0_0_17737552_18493.cpp:6:29: error: 'scanf' was not declared in this scope
     while(scanf("%d%d",&n,&m)!=EOF)
                             ^
0_0_17737552_18493.cpp:6:32: error: 'EOF' was not declared in this scope
     while(scanf("%d%d",&n,&m)!=EOF)
                                ^
0_0_17737552_18493.cpp:14:36: error: 'cmp' was not declared in this scope
         qsort(c+1,m+n,sizeof(c[0]),cmp);
                                    ^
0_0_17737552_18493.cpp:14:39: error: 'qsort' was not declared in this scope
         qsort(c+1,m+n,sizeof(c[0]),cmp);
                                       ^
0_0_17737552_18493.cpp:21:45: error: 'printf' was not declared in this scope
                 if(b[i]==0){printf("%d",c[i]);
                                             ^