13.fstream

#include <bits/stdc++.h>
using namespace std;
int main(){
    int a , b , c;
    fstream file , file2;
    file.open("sample.txt" , ios::in);
    file >> a >> b >> c;
    cout << a << " " << b  << " " << c << endl;
    file2.open("sample.txt" , ios::out | ios::trunc);
    file2 << a + b << " " << a - b << " " << a * b << "!";
    return 0;
}