Explain this C Code: Calculate Sun of 5 digits
int num,a,n;
int sum=0;
system("cls");
printf("Enter a five digit number\n");
scanf("%d",&num);
a=num%10;
n=num/10;
sum=sum+a;
a=n%10;
n=n/10;
sum=sum+a;
a=n%10;
n=n/10;
sum=sum+a;
a=n%10;
n=n/10;
sum=sum+a;
a=n%10;
sum=sum+a;
printf("The sum of the five digits of %d is %d\n",num,sum);