#include<stdio.h>
int main()
{
double sum;
int i;
for(sum=0,i=1;i<=100;i++)
{
if(i%2==1)
{
sum+=1.0/i;
}
else if(i%2==0)
{
sum-=1.0/i;
}
}
printf("結果:%lf",sum);
return 0;
}