#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

enum struct InputMode { HackerRank, Linux };
InputMode inputMode = InputMode::Linux;

using TestCasesMap = map<string,tuple<string,string>>;

TestCasesMap testCases = {
    // test   values               expected result
    // ----   ------------------   ---------------
    {  "5",   {"10 40 30 50 20",   "14.1"}},
};

TestCasesMap::const_iterator testCase = testCases.find("5");

/*
 * Complete the 'stdDev' function below.
 *
 * The function accepts INTEGER_ARRAY arr as parameter.
 */

void stdDev(vector<int> arr) {
    // Print your answers to 1 decimal place within this function

    double sum = accumulate(arr.begin(), arr.end(), 0);
    double mean = sum/arr.size();

    double stdDeviation = 0;
    
    for (size_t i = 0; i < arr.size(); i++)
    {
        stdDeviation += pow(arr[i] - mean, 2);
    }

    stdDeviation = sqrt(stdDeviation/arr.size());    
    cout << "expected: " << get<1>(testCase->second)
         << " actual: " << fixed << setprecision(1) << stdDeviation << endl;
    cout << fixed << setprecision(1) << stdDeviation << endl;
}

int main()
{
    string n_temp;
    if (inputMode == InputMode::HackerRank)    
        getline(cin, n_temp);
    else
        n_temp = testCase->first;

    int n = stoi(ltrim(rtrim(n_temp)));

    string vals_temp_temp;
    if (inputMode == InputMode::HackerRank)    
        getline(cin, vals_temp_temp);
    else
        vals_temp_temp = get<0>(testCase->second);

    vector<string> vals_temp = split(rtrim(vals_temp_temp));

    vector<int> vals(n);

    for (int i = 0; i < n; i++) {
        int vals_item = stoi(vals_temp[i]);

        vals[i] = vals_item;
    }

    stdDev(vals);

    return 0;
}

std::function<int(int)> f_isspace = [](int x){ return isspace(x); };

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not_fn(f_isspace))
        );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not_fn(f_isspace)).base(),
        s.end()
        );

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}