#include<bits/stdc++.h>
using namespace std;
#define ri register double
typedef long long LL;
double ans;
inline double f(double x){
	double sum=1;
	for(ri i=1;i<=x;++i)sum*=i;
	int a=sum/(x*x);
	return (sum/(x*x))-a;
}
int main(){
	double n,m;
	scanf("%lf%lf",&n,&m);
	for(ri i=1;i<=n;++i){
		for(ri j=1;j<=m;++j){
			ans+=f(i*j);
		}
	}
	cout<<fixed<<setprecision(5)<<ans;
	return 0;
}

rt,一直输出的是inf，求帮助，之前还以为是printf的问题，现在换成cout还是错