#include <stdio.h>

int main(){

  int check;
  int i = 0;
  while(i != 1){
   
    printf("Enter number\n");
    if((check = scanf("%d",&i)) != 1){
      printf("Error in input, must be a number \n");
      // fflush(stdin);
          setbuf(stdin,NULL);   
    }
  }
}