View Compilation Error

0_0_19512667_19699.cpp: In function 'int main(int, char**)':
0_0_19512667_19699.cpp:3:26: error: 'scanf' was not declared in this scope
    while(1==scanf("%d",&a)){
                          ^
0_0_19512667_19699.cpp:4:32: error: 'printf' was not declared in this scope
     printf("%d\n\n",((1+a)*a)/2);
                                ^