города на первую букву

#include <iostream>
#include <string>
#include <algorithm>
#include <set>
#include <vector>

using namespace std;

template <typename RandomIt>
pair<RandomIt, RandomIt> FindStartsWith(RandomIt range_begin, RandomIt range_end, char prefix) {
    auto begin = range_begin;
    auto end = range_begin;
    bool isstart=true;
    int count_start=0;
    int count_end=0;
    int count=0;

    for (auto it1 = range_begin; it1 != range_end; ++it1) {
        string a = *it1;
        if (isstart&&(a[0] == prefix)){
        isstart=false;
        count_start=count;
        count_end=count;
        }
        if (!isstart&&(a[0] == prefix)){
        count_end=count;
        }
        cout << "s:"<<count_start<<" e:"<<count_end<<" t:"<< count <<endl;
        ++count;
        }

        int i=0;
        for (auto it1 = range_begin; it1 != range_end; ++it1){
        if (i<count_start) ++begin;
        if (i<=count_end) ++end;
        ++i;
        }

    return {begin, end };
}

int main() {
    const vector<string> sorted_strings = {"astrax", "moscow", "murmansk", "mwb", "vologda"};
    const auto m_result = FindStartsWith(begin(sorted_strings), end(sorted_strings), 'a');
    for (auto it = m_result.first; it != m_result.second; ++it) {
        cout << *it << " ";
    }
    cout << endl;
    const auto p_result = FindStartsWith(begin(sorted_strings), end(sorted_strings), 'p');
    cout << (p_result.first - begin(sorted_strings)) << " " << (p_result.second - begin(sorted_strings)) << endl;
    const auto z_result = FindStartsWith(begin(sorted_strings), end(sorted_strings), 'z');
    cout << (z_result.first - begin(sorted_strings)) << " " << (z_result.second - begin(sorted_strings)) << endl;
    return 0;
}