#![allow(unused_imports)]

use std::cmp::{self, Ordering};
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::fmt::{self, Debug, Display};
use std::io::{self, Read};
use std::str::{self, FromStr};


fn solve(h: usize, w: usize, a: Vec<String>) -> bool {
    let counter = {
        let mut counter = [0; 26];
        for s in a.into_iter() {
            for &c in s.as_bytes() {
                counter[c as usize - 'a' as usize] += 1;
            }
        }
        counter
    };

    if h % 2 == 0 && w % 2 == 0 {
        return counter.into_iter().all(|n| n % 4 == 0);
    }
    let num_odds = counter.iter().filter(|&n| n % 2 == 1).count();
    let num_mod2s = counter.iter().filter(|&n| n % 2 == 0 && n % 4 > 0).count();
    if h % 2 == 0 {
        num_odds == 0 && 2 * num_mod2s <= h
    } else if w % 2 == 0 {
        num_odds == 0 && 2 * num_mod2s <= w
    } else {
        num_odds == 1 && 2 * num_mod2s <= h + w - 2
    }
}


fn main() {
    let stdin = io::stdin();
    let mut sc = Scanner::new(stdin.lock().bytes());
    let (h, w) = (sc.next(), sc.next());
    print_yesno(solve(h, w, sc.vec(h)), "Yes", "No");
}


struct Scanner<R: Read> {
    buf: Vec<u8>,
    bytes: io::Bytes<R>,
}

#[allow(dead_code)]
impl<R: Read> Scanner<R> {
    fn new(bytes: io::Bytes<R>) -> Self {
        Scanner {
            buf: Vec::with_capacity(256),
            bytes: bytes,
        }
    }

    fn next<T: FromStr>(&mut self) -> T
    where
        <T as FromStr>::Err: Debug,
    {
        self.buf.clear();
        for c in self.bytes
            .by_ref()
            .map(|c| c.unwrap())
            .skip_while(|&c| c == ' ' as u8 || c == '\n' as u8)
            .take_while(|&c| !(c == ' ' as u8 || c == '\n' as u8))
        {
            self.buf.push(c);
        }
        str::from_utf8(&self.buf).unwrap().parse().unwrap()
    }

    fn vec<T: FromStr>(&mut self, n: usize) -> Vec<T>
    where
        <T as FromStr>::Err: Debug,
    {
        (0..n).map(|_| self.next()).collect()
    }

    fn pairs<A: FromStr, B: FromStr>(&mut self, n: usize) -> Vec<(A, B)>
    where
        <A as FromStr>::Err: Debug,
        <B as FromStr>::Err: Debug,
    {
        (0..n).map(|_| (self.next(), self.next())).collect()
    }

    fn trios<A: FromStr, B: FromStr, C: FromStr>(&mut self, n: usize) -> Vec<(A, B, C)>
    where
        <A as FromStr>::Err: Debug,
        <B as FromStr>::Err: Debug,
        <C as FromStr>::Err: Debug,
    {
        (0..n)
            .map(|_| (self.next(), self.next(), self.next()))
            .collect()
    }

    fn mat<T: FromStr>(&mut self, m: usize, n: usize) -> Vec<Vec<T>>
    where
        <T as FromStr>::Err: Debug,
    {
        (0..n).map(|_| self.vec(m)).collect()
    }
}


#[allow(dead_code)]
fn print_yesno(x: bool, yes: &'static str, no: &'static str) {
    println!("{}", if x { yes } else { no });
}


#[allow(dead_code)]
fn print_foreach<T: Display, I: IntoIterator<Item = T>>(xs: I) {
    for x in xs.into_iter() {
        println!("{}", x);
    }
}


#[allow(dead_code)]
fn print_or<T: Display>(x: Option<T>, or: &'static str) {
    if let Some(x) = x {
        println!("{}", x);
    } else {
        println!("{}", or);
    }
}


Measured memory_bytes: 4352