#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
#include <map>

using namespace std;

int main()
{
#ifdef _DEBUG
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
#endif
	string str = "abcdefghijklmnopqrstuvwxwzABCDEFGHIJKLMNOPQRSTUVWXYZ";
	vector <string> a;
	map <unsigned char, float> m;
	while (cin)
	{
		string s;
		getline(cin, s);
		if (s != "")
		{
			a.push_back(s);
		}
	}
	for (int i = 0; i < a.size(); ++i)
	{
		for (int j = 0; j < a[i].length(); ++j)
		{
			if (isalpha(a[i][j]))
			{
				if (m.find(a[i][j]) == m.end())
					m.insert(make_pair(a[i][j], 1));
				else
					m.find(a[i][j])->second++;
			}
		}
	}
	for (auto it = m.begin(); it != m.end(); ++it)
	{
		for (int i = 0; i < str.length(); ++i)
		{
			if (m.find(str[i]) == m.end())
				m.insert(make_pair(str[i], 0));
		}
	}
	int n = 0;
	for (int i = 0; i < a.size(); ++i)
		n += a[i].length();
	for (auto it = m.begin(); it != m.end(); ++it)
	{
		cout << it->first << ": ";
		printf("%.3f",it->second/n);
		cout << endl;
	}
    return 0;
}