View Compilation Error

0_0_33203459_12419.cpp: In function 'int main()':
0_0_33203459_12419.cpp:5:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                     ^
0_0_33203459_12419.cpp:5:24: error: 'EOF' was not declared in this scope
  while(scanf("%d",&n)!=EOF)
                        ^
0_0_33203459_12419.cpp:7:30: error: 'printf' was not declared in this scope
   printf("%lld\n\n",n*(n+1)/2);
                              ^