#include<stdio.h>
 
/* Function to find the sum of the multiples
of a OR b between 1 and N, excluding N */ 
 
int findSum(int a, int b, int N){
    N--;
    int a_n = (N/a)*a, b_n = (N/b)*b, ab_n = (N/(a*b))*a*b;
    int sum_a = ((N/a) * (a + a_n))/2;
    int sum_b = ((N/b) * (b + b_n))/2;
    int sum_ab = ((N/(a*b)) * (a*b + ab_n))/2;
    return sum_a + sum_b - sum_ab;
}
 
int main(){
    int a = 3, b = 5, N = 1000;
    printf("%d", findSum(a, b, N));
}

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