`\color{pink}{#Bơ}`

$\rm C++$

#include <bits/stdc++.h>
#define db double
using namespace std;

int main() {
    db x, s = 1, t = 1;
    cin >> x;
    for (int i = 1;; ++i) {
        t *= x / i;
        if (t < 1e-9) break;
        s += t;
    }
    cout << fixed << setprecision(4) << s;
}

$\rm Python$

x = float(input())
s = t = 1
i = 1
while True:
    t *= x / i
    if t < 1e-9:
        break
    s += t
    i += 1
print(f"{s:.4f}")

 `\color{#1AD5F7}{꧁⋆⟡T}\color{#1AD5F7}{D}\color{#4DA6E6}{u}\color{#668EDD}{n}\color{#8077D5}{g}\color{#995FCD}{G}\color{#EA2F90}{M⟡⋆꧂}`