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

int main()
{

	vector<char> alphabet;

	cout << "Please input a sentence (please input lowercase)";
	string sentence;
	getline(cin, sentence); //cin is limiting, replaced with getline.
	if (!cin) {
		cout << "That isn't a sentence.\n";
		return EXIT_FAILURE;
	}

	for (int i {0}; i < sentence.size(); ++i) {
		char c = sentence[i];
		if (c >= 'a' && c <= 'z') {
			alphabet.push_back(c);
		}
	}

	vector<char>::size_type n {alphabet.size()};

	int mostused {0};
	char freqletter {'a'};

	for (int i {0}; i < n; ++i) {
		int count {0};
		char letter = alphabet[i];
		
		for (int k {0}; k < n; ++k){
			if (alphabet[k] == letter) {
				++count;
			}
		}
		if (count > mostused) {
			mostused = count;
			freqletter = letter;
		}
	}	
	
	cout << "Your sentence has the letter, " << freqletter << ", used" << " " << mostused;
	
	if (mostused == 1) {
		cout << " time.\n";
	} else {
		cout << " times.\n";
	}

	return EXIT_SUCCESS;
}