function pickingNumbers(a: number[]): number {
    
    // sort arr in ascding order
    a.sort((x,y)=>x-y);
    
    let ans = 0;
    let window_start = 0;
    
    for (let window_end = 0; window_end < a.length; window_end++) {
        
        while (a[window_end] - a[window_start] > 1) {
            window_start ++;
        }
        
         const window_size = window_end - window_start +1;
         
         ans = Math.max(window_size, ans);
    }
    
    return ans;
}