fact

#include<iostream>
#include<stdio.h>
using namespace std;


int main() {
    int b, factb= 1, factc = 1, sum = 0;
    cout << "b= "; cin >> b;
    for(int i = 1; i <= b; i++) factb *= i;
    for (int i = 1; i <= b; i++) {
        sum += factb / factc;
        factc *= i + 1;
    }
    cout << "Rezultatul este: " << (double)sum/factb<<endl;
}