uva 1388 - Graveyard(贪心)

int main()
{
#ifndef ONLINE_JUDGE
freopen("in","r",stdin);
freopen("out","w",stdout);
#endif
int n, m;
while(~scanf("%d%d", &n, &m))
{
double ans = 0.0;
for(int i = 1; i < n; ++i)
{
double t = (double)i/n*(n+m);
ans += fabs(t-floor(t+0.5))/(n+m);
}
printf("%.4lf\n", ans*10000);
}
return 0;
}