Can someone give me suggestions on how to improve this program?The objective is to find the sum of all the multiples of 3 or 5 below 1000.#include <stdio.h>main(){    int S, s3,s2,S1;    int a=333,b=3,c=999, i=5,j=995, k=199, m = 15, n= 66, o= 990;    S1= a*(b+c)/2;    s2= k*(i+j)/2;    s3= n*(m+o)/2;    S= S1 + s2 - s3;    printf(sum is:%d,S);    return 0;}
Please review my solution to Project Euler program 1
c;project euler