static int _min(int x, int y){
    return x < y? x: y;
}

static int _max(int x, int y){
    return x > y? x: y;
}

static int _div(int x, int y){
    /* y is assumed to be non-negative */
    if(x < 0)return (x - (y-1)) / y;
    return x / y;
}

static int _rem(int x, int y){
    /* y is assumed to be non-negative */
    if(x < 0)return (y - 1) + (x - (y-1)) % y;
    return x % y;
}