#include <iostream>
#include <string>
#include <vector>
using namespace std;

typedef vector<double> Abecedario;

int main() {
    // 4 cifras de precisión
    cout.setf(ios::fixed);
    cout.precision(4);
    
    Abecedario a(26, 0);
    char c;
    while(cin >> c) {
        if(c >= 'a' and c <= 'z') ++a[c-'a'];
        else if(c >= 'A' and c <= 'Z') ++a[c-'A'];
    }
    
    string s = "abcdefghijklmnopqrstuvwxyz";
    double suma = 0;
    for(int i = 0; i < 26; ++i) suma+= a[i];
    cout << int(suma) << " letras" << endl;
    for(int i = 0; i < 26; ++i) {
        double k = a[i]/suma*100;
        if(a[i] != 0) cout << s[i] << ": " << k << "%" << endl;
    }
}