Counting the Letters

#include <iostream>
#include <string>
using namespace std;
    int main () {
        string ed;
        char letter;
        int izon, count = 0;
        system("cls");
        cout << "Problem 4 - Counting Letter" << endl;
        cout << "--------------------------------\n";
        cout << "Enter Text: ";
        getline (cin, ed);
        cout << "Letter to count: ";
        cin >> letter;
        izon = ed.length();

            while (izon>0){
                izon--;
                if (ed[izon]==letter){
                    count++;
            }

            }
            cout << count << " Letter " << letter << "!" << endl;

    return 0;
    }