INT error (HELP!!!)

I have an error 'level' was not declared in this scope please help!!!

This is a code:

void setup() {
  // put your setup code here, to run once:

 int level=0;
 pinMode(3,OUTPUT);
 pinMode(5,OUTPUT);
 pinMode(6,OUTPUT);
 
}

void loop() {
  // put your main code here, to run repeatedly:
analogWrite(3,level);

level+1=level;
delay (100);
}

You are declaring level in setup(). When setup() finishes, level goes out of scope and no longer exists. Declare and initialize level outside of setup() (make it global) or declare and initialized level in loop() (make it local to loop().