#include<stdio.h>
#include<math.h>
int main()
{
    double n,sum=0;
    scanf("%lf",&n);
    for(int i=1;i<=n;i++)
    {
        sum+=pow(-1,i-1)*(1.0/i);
    }
    printf("%.4lf",sum);
    return 0;
}
```


```

#include <stdio.h>
int main()
{
    int n=0;
    scanf("%d",&n);
    double i=1;
    double sum=0;

    for (double num=1.0;num<=n;num++){
        sum=sum+1/num*i;
        i*=-1;
    }
    printf("%.4lf",sum);
    return 0;
}