increment and decrement operator

/* increment and decrement operator pre and post*/
#include<stdio.h>
#include<conio.h>
int main()
{
    int a=30,b=40;
    printf("\nvalue of a is %d",--a);
    printf("\nvalue of a is %d",a);
    ( a++ + --b + ++b - a-- )
    return 0;
}