// Continued fraction A
#include <string.h>
#include <ctype.h>
#include <stdio.h>

#define SIZE 100

float calculate(int a[SIZE], int n, int i) {
    if(i == n-1) {
        return a[i];
    }
    else {
        return a[i] + 1/calculate(a, n, ++i);
    }
}

int main() {

    int n, i;
    int a[SIZE];

    scanf("%d", &n);
    for(i = 0; i < n; i++) {
        scanf("%d", &a[i]);
    }

    printf("%.2f", calculate(a, n, 0));

    return 0;
}