Universe is random, But is it?

#include<bits/stdc++.h>

using namespace std;

#define sp << " " <<
#define mod 1000000007
#define mp make_pair
#define pb push_back
#define int long long
#define double long double
#define INF 1e18
#define PI 3.14159265359

int power(int p,int y)
{
    int res=1;
    p=p%mod;
    while(y>0)
    {
        if(y&1)
            res=(res*p)%mod;
        y=y>>1;
        p=(p*p)%mod;
    }
    return res;
}

/*
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int dice()
{
    uniform_int_distribution<int> uid(0,1);//specify l and r.
    return uid(rng) ;
}

int read()
{
       int cc = getc(stdin);
       for (;cc < '0' || cc > '9';)  cc = getc(stdin);
       int dp = 0;
       for (;cc >= '0' && cc <= '9';)
       {
          dp = dp * 10 + cc - '0';
          cc = getc(stdin);
       }
      return dp;
}

inline void print(int n)
{
  if (n == 0)
  {
    putchar('0');
    putchar('\n');
  }
  else if (n == -1)
  {
    putchar('-');
    putchar('1');
    putchar('\n');
  }
  else
  {
    char buf[20];
    buf[19] = '\n';
    int i = 18;
    while (n)
    {
      buf[i--] = n % 10 + '0';
      n /= 10;
    }
    while (buf[i] != '\n')
      putchar(buf[++i]);
  }
}

int n;

vector<vector<int>> mat_mul(vector<vector<int>> a,vector<vector<int>> b)
{
    int n=5;
	vector<vector<int>> t(n,vector<int>(n,0));
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<n;j++)
		{
			for(int k=0;k<n;k++)
			{
				t[i][j]+=((a[i][k]*b[k][j])%mod);
				t[i][j]%=mod;
			}
		}
	}
	return t;
}

vector<vector<int>> pow_mat(vector<vector<int>> mat_a,int p)
{
	if(p==1)
        return mat_a;
	vector<vector<int>> temp=pow_mat(mat_a,p/2);
	vector<vector<int>> res=mat_mul(temp,temp);
	if(p&1)
        res=mat_mul(res,mat_a);
	return res;
}
*/

int32_t main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    freopen("sample_input.txt", "r", stdin);
    freopen("sample_output.txt", "w", stdout);
    int n,k,e;
    double m;
    cin >> n >> m >> k >> e;
    double dp=(double)m/2;
    for(int i=0;i<k;i++)
    {
        double d=floor(dp);
        dp=((d+1)*dp+(m*(m+1))/2-(d*(d+1))/2)/(m+1);
    }
    cout << fixed << setprecision(6) << dp;
    return 0;
}