#include <iostream>
using namespace std;

int sum(int a, int b) { //formal parameters
    int rslt = a + b;
    return rslt;
}

int max(int i, int j) {
    if (i >= j) return i;
    return j;
}

void intro() {
    int i = 5, j = 7, k = 1;
    int r = sum(i, j); //actual parameters, arguments
    cout << r << " " << sum(j, k) << endl;
    cout << sum(k, sum(j, j));
}

void increment1(int k) {
    k++;
    cout << k << endl;
}

void increment2(int& k) {
    k++;
    cout << k << endl;
}


void passByValueOrReference() {
    int a = 0;
    increment1(a);
    cout << a << endl;
    a=0;
    increment2(a);
    cout << a << endl;
}

int preIncrement(int& i) {
    i=i+1;
    return i;
}

int postIncrement(int& i) {
    int l=i;
    i=i+1;
    return l;
}

double power(double basi, int ekthetis) {
    if (ekthetis==0) return 1;
    double rVal=1;
    for (int i=0; i<ekthetis; i++)
        rVal=rVal*basi;
    return rVal;
}

int paragontiko(int num) {
    if (num==0) return 1;
    int x=1;
    for (int i=num; i>=1; i--)
        x=x*i;
    return x;
}

void prt2Powers() {
    for (int ekt=0; ekt<=16; ekt++)
        cout << "2 stin " << ekt << " equals to " << power(2,ekt) << endl;
}

int main(int argc, char** argv) {
    intro();
    passByValueOrReference();
    cout << power(2,4) << endl;
    prt2Powers();
    for (int i=0; i<5; i++)
        cout << i << " " << paragontiko(i) << endl;
    
    return 0;
}