micro:bit Game Block Running Control with A and B Button

let x_winning = 0
let score = 0
let start = false
let agent = 0
let difficulty = 0
let j = 0
input.onButtonPressed(Button.A, () => {
    led.unplot(agent, 4)
    if (agent > 0) {
        agent += -1
    }
    led.plot(agent, 4)
})
input.onButtonPressed(Button.B, () => {
    led.unplot(agent, 4)
    if (agent < 4) {
        agent += 1
    }
    led.plot(agent, 4)
})
input.onGesture(Gesture.Shake, () => {
    if (!(start)) {
        basic.clearScreen()
        led.stopAnimation()
    }
    start = true
})
j = 0
difficulty = 500
score = 0
start = false
x_winning = 0
agent = 2
basic.forever(() => {
    if (start) {
        led.plot(agent, 4)
        x_winning = Math.random(5)
        for (let i = 0; i <= 4; i++) {
            for (let k = 0; k <= 4; k++) {
                led.plot(k, i)
            }
            led.unplot(x_winning, i)
            if (i == 4) {
                led.plot(agent, 4)
                if (agent != x_winning) {
                    basic.showString("Game over! Score", 75)
basic.showNumber(score)
                    basic.pause(2000)
                    control.reset()
                }
            }
            basic.pause(difficulty)
            for (let l = 0; l <= 4; l++) {
                led.unplot(l, i)
            }
            if (i == 4) {
                led.plot(agent, 4)
            }
        }
        score += 1
        if (difficulty > 75) {
            difficulty = difficulty - 20
        }
    } else {
        basic.showString("Shake it off!", 70)
    }
})