#include <stdio.h>
#include <stdlib.h>
#include <math.h>

double getSum(int a){ //返回值要是double才行，不然x最大的时候验证不通过
    double count = 1;
    while(a>0){
        count *= a;
        a--;
    }
    return count;
}
int main(){
    double x,count = 1;
    int i = 1;
    scanf("%lf",&x);
    while(pow(x,i)/getSum(i) >= 0.00001){
        count += pow(x,i)/getSum(i);
        i++;
    }
    count += pow(x,i)/getSum(i); //最后一项的绝对值小于0.00001
    printf("%.4lf",count);
}