class num_show {
  float x;
  float y;
  float zene;
  String[] chat = {
    "+", "-", "*"
  };
  int zened;
  int a;
  int b;
  int answer;
  int play;

  void difficulty(int p) {
    if (p == 1) {
      play = 10;
    }
    else if (p == 2) {
      play = 100;
    }
    else if (p == 3) {
      play = 1000;
    }
  }
  void setup() {
    next();
    display();
  }

  int next() {
    x = random(0, play);
    y = random(0, play);
    zene = random(0, 3);
    zened = int(zene);
    a = int(x);
    b = int(y);
    if (zened == 0) {
      answer = a+b;
    }
    else if (zened == 1) {
      answer = a-b;
    }
    else if (zened == 2) {
      if(play>=100){
      a = a%(play/10);
      b = b%(play/10);
      }
      answer = a*b;
    }
    return answer;
  }
  void display() {
    fill(255);
    rect(50,210,280,55);
    fill(0);
    textAlign(CENTER);
    textSize(30);
    text(a + chat[zened] + b + "=", 150, 250);
  }
  void check(char key) {
    if (key == ENTER) {
      if (int(num) == ans) {
        ans = number.next();
        if (stack<6) {
          stack++;
        }
      }
      num = "";
    }
    else if (key == BACKSPACE) {
      num = "";
    }
    else {
      num = num + str(key);
    }
  }
}