7

class  {
    public int reverse(int x) {
        int t = x;
        int num = 0;
        while(t!=0){
            int temp = num*10 + t%10;
            if((temp-t%10)/10 != num){
                return 0;
            }
            num = temp;
            t=t/10;
        }
        return num;
    }
}