求助大佬们

这道题应该怎么编程啊？为什么我写的程序最后是输出运算结果啊。
#include <stdio.h>
int main() {
int n;
double result = 0;
printf("Please write down a num: ");
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
if (i % 2 == 1) {
result += 1.0 / i;
} else {
result -= 1.0 / i;
}
}
printf("The answer is: %lf\n", result);
return 0;
}