// https://atcoder.jp/contests/abc147/tasks/abc147_f
//
#![allow(unused_imports)]
use std::io::*;
use std::io::Write;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

// Input macros.
// Original by tanakh: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };

    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, [ next / $t:tt ]) => {
        {
            let len = read_value!($iter, usize);
            (0..len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        }
    };

    ($iter:expr, switch) => {
        {
            let ty = read_value!($iter, i32);
            if ty == 1 {
                vec![ty, read_value!($iter, i32), read_value!($iter, i32)]
            } else if ty == 2 {
                vec![ty, read_value!($iter, i32)]
            } else {
                vec![ty, read_value!($iter, i32)]
            }
        }
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! read_line {
    ($t:tt) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).unwrap();
            s.trim_right().parse::<$t>().unwrap()
        }
    }
}

#[allow(unused_macros)]
macro_rules! dvec {
    ($t:expr ; $len:expr) => {
        vec![$t; $len]
    };

    ($t:expr ; $len:expr, $($rest:expr),*) => {
        vec![dvec!($t; $($rest),*); $len]
    };
}

#[allow(unused_macros)]
macro_rules! ifv {
    ($t:expr, $a:expr, $b: expr) => {
        if $t { $a } else { $b }
    }
}

#[allow(unused_macros)]
macro_rules! fill {
    ($t:expr, $v:expr) => {
        for i in 0..$t.len() {
            $t[i] = $v;
        }
    };
}

#[allow(unused_macros)]
macro_rules! join {
    ($t:expr, $glue:expr) => {
        $t.into_iter().map(|w| w.to_string()).collect::<Vec<_>>().join($glue)
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

// ===

fn sum(x: i64, d: i64, i: usize, j: usize) -> i64 {
    let f = x + d * (i as i64);
    let t = x + d * (j as i64);
    (f + t) * ((j - i + 1) as i64) / 2
}

fn gid(s: i64, d: i64) -> i64 {
    (d+s%d)%d
}

fn solve(n: usize, x: i64, d: i64) -> i64 {
    if d == 0 {
        if x == 0 {
            return 1;
        }
        return (n+1) as i64;
    }
    let mut ranges = vec![];
    ranges.push((0, 0));
    for i in 1..n+1 {
        let less_i = sum(x, d, 0, i-1);
        let more_i = sum(x, d, n-i, n-1);
        ranges.push((min(less_i, more_i), max(less_i, more_i)));
    }
    let d = ifv!(d < 0, -d, d);
    let mut hset = HashMap::new();
    for &(s, t) in &ranges {
        let mo = (d+s%d)%d;
        hset.insert(mo, vec![]);
    }
    for &(s, t) in &ranges {
        let mo = (d+s%d)%d;
        hset.get_mut(&mo).unwrap().push((s, t));
    }

    let mut total = 0;
    for (k, v) in hset {
        let mut v = v.clone();
        v.sort();

        total += (v[0].1-v[0].0+d)/d;
        let mut head = v[0].1;
        v.remove(0);

        for (f, t) in v {
            // debug!(head, total, f, t);
            if head < f {
                head = t;
                total += (t-f+d)/d;
            } else {
                if head < t {
                    total += (t-head)/d;
                    head = t;
                }
            }
        }
    }
    total
}

fn main() {
    input! {
        n: usize, x: i64, d: i64
    };

    println!("{}", solve(n, x, d));
}


Measured memory_bytes: 30984