Помогите c++ 2017

как решить ошибки?
(оставил на них комментарии)









#include "pch.h"
#include <cstdlib>
#include <iostream>
using namespace std;

int main()
{
int a;
int b;
int c = 100;
int d;
cout << "Hello" << endl;
cout << "You have 100 coins" << endl;
cout << "Your task is to earn 1000 coins choosing a color in roulette — black x2(48 % )" << endl;
cout << "red x3(32 % ), blue x5(18 % ) and gold x50(2 % )" << endl;
while (c < 10000) {
cout << "Enter how many coins you want to put : " << endl;
cin >> a;
while (a > c)
{
cout << "You do not have many coins" << endl;
cout << "Enter how many coins you want to put : " << endl;
cin >> a;
}
cout << "Chose color(1 — black; 2 — red; 3 — blue; 4 — gold)" << endl;
cin >> b;
while (b > 4)
{
cout << "Enter a number from 1 to 4 (1 — black; 2 — red; 3 — blue; 4 — gold)" << endl;
cin >> b;
}
while (b < 0) {
cout << "Enter a number from 1 to 4 (1 — black; 2 — red; 3 — blue; 4 — gold)" << endl;
cin >> b;
}
d = rand() % 54 + 1;
cout << "Fell out " << d << endl;
if (b == 1) {
if (d < 27) {
c = c + a;
cout << "You won.You have " << c << " coins" << endl;
}
else {
c = c - a;
cout << "You lose.You have " << c << " coins" << endl;
}
}
else
if (b == 2) {
if (26 < d < 44) {
c = c + a2; //ЗДЕСЬ ОШИБКА идентификатор a2 не определён
cout << "You won.You have " << c << " coins" << endl;
}
else {
c = c - a;
cout << "You lose.You have " << c << " coins" << endl;
}
}
else
if (b == 3) {
if (43 < d < 54)
{
c = c + a4; //ЗДЕСЬ ОШИБКА идентификатор a4 не определён
cout << "You won.You have " << c << " coins" << endl;
}
else {
c = c - a;
cout << "You lose.You have " << c << " coins" << endl;
}
}
else
if (b == 4)
{
if (d == 54)
{
c = c + a * 49;
cout << "You won.You have " << c << " coins" << endl;
}
else {
c = c - a;
cout << "You lose.You have " << c << " coins" << endl;
}
}
}
if (c > 10000) {
cout << "Congratulations !You won this game.You have " << c << " coins" << endl;
}
system("pause");
return 0;