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#include<bits/stdc++.h>
#define RG register
#define file(x) freopen(#x".in", "r", stdin);freopen(#x".out", "w", stdout);
#define clear(x, y) memset(x, y, sizeof(x));
using namespace std;
inline int read()
{
int data=0, w=1;
char ch=getchar();
while(ch!='-'&&(ch<'0'||ch>'9')) ch=getchar();
if(ch=='-') w=-1, ch=getchar();
while(ch>='0'&&ch<='9') data=(data<<3)+(data<<1)+(ch^48), ch=getchar();
return data*w;
}
const int maxn(210);
int n;
long double ans, f[maxn][2], g[maxn], m;
int main()
{
n=read(); m=read();
g[1]=f[0][1]=1.0000;
for(RG int i=2;i<=n;i++) g[i]=g[i-1]/m;
for(RG int i=0;i<n;i++)
for(RG int j=i+1;j<=n;j++)
{
f[j][0]+=(j-i)*g[j-i]*(f[i][0]*(m-2.0000)/m+f[i][1]*(m-1.0000)/m);
f[j][1]+=(j-i)*g[j-i]*f[i][0]/m;
}
ans=g[n]*n;
for(RG int i=1;i<n;i++) ans+=1.0000*i*i*f[n-i][0]*g[i];
printf("%.10Lf\n", ans);
return 0;
}
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