// 编写递归函数求s=1/(m*(m+1))+…+1/(n*(n+1)),其中,1<=m<=n
//输出超限?
#include
float fun(int m, int n)
{
int i;
float s=0;
for (i = m; i <= n; i++)
s = s + 1.0 / (i * (i + 1));
return s;
}
int main()
{
int m, n;
while (scanf("%d,%d", &m, &n))
{
if (m >= 1 && m <= n)
printf("%f\n", fun(m, n));
else
printf("Error\n");
}
return 0;
}