View Compilation Error

0_0_37378043_892.cpp: In function 'int main()':
0_0_37378043_892.cpp:4:27: error: 'scanf' was not declared in this scope
  while(scanf("%d %d",&M,&N),M!=-1||N!=-1){
                           ^
0_0_37378043_892.cpp:34:21: error: 'printf' was not declared in this scope
   printf("%.3lf",sum); 
                     ^