Grade calculator

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <math.h>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <fstream>
#include <iomanip>
#include <windows.h>
typedef long long ll;
using namespace std;
void findCount(ifstream &read,string s) {
    read.open(s);
    vector<char> Grade;
    string temp;
    cout << setprecision(2) << showpoint << fixed;
    while (getline(read, temp)) {
        int Grade_finder = temp.size();
        Grade.push_back(temp[Grade_finder - 1]);
    }
    sort(Grade.begin(), Grade.end());
    float counter = 0, total = Grade.size() - 1;
    for (int i = 0; i < total; i++) {
        if (Grade[i] == Grade[i + 1]) {
            counter++;
        }
        else {
            counter++;
            float average = (counter / total) * 100;
            cout << "Number of student with the grade: " << Grade[i] << " is " << (int)counter << endl;
            cout << "The percentage of the student with grade " << Grade[i] << " is " << (int)average << "% \n";
            counter = 0;
        }//corner case
        if ((i + 1) == total) {
            counter++;
            cout << "Total abscent students are: " << (int)counter << endl;
            break;
        }
    }
    cout << "Total student attended: " << Grade.size()<<"\n";
    read.close();
}

int main() {
    ifstream read,math,checker;
    string s;
    cout << "INTRODUCTION TO PROGRAMMING GRADES \n";
    s = "Grades.txt";
    findCount(read,s);
    cout << "MATHEMATICS FOR COMPUTER SCIENTIST GRADES \n";
    s = "MathGrade.txt";
    findCount(math,s);
    s = "Checker.txt";
    tellgdetector(checker,s);
}