#include <iostream>

using namespace std;

const char EOT = '\0';

struct appear {
    char ch;
    int n_appearances;
};
typedef struct appear APPEAR;

void appearances(char* str, APPEAR appear_arr[], int &n);

void appearances(char* str, APPEAR appear_arr[], int &n) {
    if (*str == EOT) {
        n = 0;
    } else {
        appearances(str + 1, appear_arr, n);
        for (int i = 0; i < n; i++) {
            if (appear_arr[i].ch == *str) {
                appear_arr[i].n_appearances++;
                return;
            }
        }
        appear_arr[n].ch = *str;
        appear_arr[n].n_appearances = 1;
        n++;
    }
}

// prints out the amount of times each letter appears in the input string
// input: a string
// output: the amount of times each letter appears in the input string
int main()
{
    const int SIZE = 100;
    char str[SIZE];
    int n;
    APPEAR res[SIZE];
    cout << "enter a string: ";
    cin.getline(str, SIZE);

    appearances(str, res, n);

    for (int i = 0; i < n; i++) {
        cout << res[i].ch << ":" << res[i].n_appearances << " ";
    }
    cout << endl;
}