#include <iostream>
#include <graphics.h>
#include <cmath>

using namespace std;

int main() {
    int gd = DETECT, gm;
    initgraph(&gd, &gm, "");

    const double distance = 208;
    const double riverSpeed = 5;
    const double timeDifference = 5;

    double boatSpeed = (distance * (riverSpeed + distance / (timeDifference + distance / riverSpeed))) / (2 * distance);

    int riverWidth = 50;
    line(50, 200, 50 + riverWidth, 200);
    line(50, 250, 50 + riverWidth, 250);
    line(50, 200, 50, 250);
    line(50 + riverWidth, 200, 50 + riverWidth, 250);

    int boatSize = 20;
    int boatX = 50 + riverWidth / 2 - boatSize / 2;
    int boatY = 220;
    rectangle(boatX, boatY, boatX + boatSize, boatY + boatSize / 2);
    line(boatX + boatSize / 2, boatY + boatSize / 4, boatX + boatSize / 2 - 10, boatY + boatSize / 4 - 10);
    line(boatX + boatSize / 2, boatY + boatSize / 4, boatX + boatSize / 2 - 10, boatY + boatSize / 4 + 10);
    line(boatX + boatSize / 2, boatY + boatSize / 4, boatX + boatSize / 2 + 10, boatY + boatSize / 4 - 10);
    line(boatX + boatSize / 2, boatY + boatSize / 4, boatX + boatSize / 2 + 10, boatY + boatSize / 4 + 10);

    char text[50];
    sprintf(text, "Boat speed: %.2f km/h", boatSpeed);
    outtextxy(10, 70, text);
    getch();
    closegraph();

    return 0;
}