MN_RR

#include <iostream>
//#define _USE_MATH_DEFINES
//#include <math.h>

using namespace std;

double h = 0.0;
int N = 0;



double f(double x, double y)
{
    return x+y;
}

double k1(double h, double x, double y)
{
    return h*f(x,y);
}

double k2(double h, double x, double y)
{
    return h*f(x + 0.5 * h, y + 0.5 * k1(h,x,y));
}

double k3(double h, double x, double y)
{
    return h*f(x + 0.5 * h, y + 0.5 * k2(h,x,y));
}

double k4(double h, double x, double y)
{
    return h*f(x + h, y + k3(h,x,y));
}

double yn(double h, double x, double y)
{
    return y + (1/6.0) * (k1(h,x,y) + 2* k2(h,x,y) + 2*k3(h,x,y) + k4(h,x,y));
}



int main ()
{
    double x0 = 0.0;
    double y0 = 0.0;

    //cout << "Podaj x0 = "; cin >> x0;
    cout << "Podaj y0 = "; cin >> y0;
    cout << "Podaj N = "; cin >> N;

    double x = x0;
    double y = y0;

    h = (y0-x0) / (double)N;

    for(int i = 0; i < N; i++)
    {
        y = yn(h,x,y);
        x += h;

    }

    cout << y;

    return 0;
}