#include <iostream>
#include <iomanip>
#include <string>
#include <stack>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <regex>
using namespace std;
using pii  = pair<int,int>;
using ll=long long;
using ld=long double;
#define pb push_back
#define mp make_pair
#define stpr setprecision
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define rep(i,n) for(ll i=0;i<(n);++i)
#define Rep(i,a,b) for(ll i=(a);i<(b);++i)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define rRep(i,a,b) for(int i=a;i>=b;i--)
#define crep(i) for(char i='a';i<='z';++i)
#define psortsecond(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.second<b.second;});
#define ALL(x) (x).begin(),(x).end()
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define endl '\n'
int ctoi(const char c){
  if('0' <= c && c <= '9') return (c-'0');
  return -1;
}
ll gcd(ll a,ll b){return (b == 0 ? a : gcd(b, a%b));}
ll lcm(ll a,ll b){return a*b/gcd(a,b);}
constexpr ll MOD=1000000007;
constexpr ll INF=1000000011;
constexpr ll MOD2=998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS=10e-8;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> istream& operator>>(istream& is,vector<T>& v){for(auto&& x:v)is >> x;return is;}
template<typename T,typename U> istream& operator>>(istream& is, pair<T,U>& p){ is >> p.first; is >> p.second; return is;}
template<typename T,typename U> ostream& operator>>(ostream& os, const pair<T,U>& p){ os << p.first << ' ' << p.second; return os;}
template<class T> ostream& operator<<(ostream& os, vector<T>& v){
    for(auto i=begin(v); i != end(v); ++i){
        if(i !=begin(v)) os << ' ';
        os << *i;
    }
    return os;
}

map<char,ll> M;
ll mo0,mo1,mo2,mo3;

int main(){
    ll  H,W;
    string S[107];
    cin >> H >> W;
    rep(i,H){
        cin >> S[i];
    }
    rep(i,H){
        rep(j,W){
            M[S[i][j]]++;
        }
    }
    for(auto P : M){
        if(P.second>0){
            if(P.second%4==0){
                mo0++;
            }
            if(P.second%4==1){
                mo1++;
            }
            if(P.second%4==2){
                mo2++;
            }
            if(P.second%4==3){
                mo3++;
            }
        }
    }
    if(H%2==0 && W%2==0){
        if(mo1==0 && mo2==0 && mo3==0){
            cYes;
        }
        else{
            cNo;
        }
    }
    else if(H%2==1 && W%2==1){
        ll T=(H/2)+(W/2);
        if(mo1+mo3==1){
            if(mo1==1){
                if(mo2<=T){
                    cYes;
                }
                else{
                    cNo;
                }
            }
            else{
                if(mo2<=T-1){
                    cYes;
                }
                else{
                    cNo;
                }
            }
        }
        else{
            cNo;
        }
    }
    else{
        if(mo1>0 || mo3>0){
            cNo;
        }
        else{
            if(H%2==1 && mo2<=W/2){
                cYes;
            }
            else if(W%2==1 && mo2<=H/2){
                cYes;
            }
            else{
                cNo;
            }
        }
    }
}

Measured memory_bytes: 256