计算n-m个数字的和

#include <stdio.h>

int main(int argc, char** argv) {
	int n,m = 0;
	scanf("%d %d", &n, &m);
	sum(n,m);
	return 0;
}

int sum(int n, int m){
	int a,b,c,d,e = 0;
	a = m-n;
	b = m+n;
	c = (b/2)-1;
	d = m/2;
	if (a%2 == 0){
		e = (b/2)+(c*b);
	}
	else{
		e = b*d;
	}
	printf("%d", e);
	return e;
}