View Compilation Error

0_0_29339662_19634.cpp: In function 'int main()':
0_0_29339662_19634.cpp:3:26: error: 'scanf' was not declared in this scope
  while(scanf("%d%d",&a,&b)!=NULL){
                          ^
0_0_29339662_19634.cpp:3:29: error: 'NULL' was not declared in this scope
  while(scanf("%d%d",&a,&b)!=NULL){
                             ^
0_0_29339662_19634.cpp:4:18: error: 'printf' was not declared in this scope
   printf("%d",a+b);
                  ^