#include <iostream>
using namespace std;
int main() {
int n;
double a;
cin >> n;
double s = 0.0;
for (int i = 0; i < n; i++){
cin >> a;
for(int j = 1; j<=i; j++){
a/= j*1.0;
}
s+=a;
}
cout << s <<"\n";
return 0;
}
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