#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T, class S> istream& operator >> (istream& is, pair<T,S>& p){return is >> p.first >> p.second;}
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T, class S> ostream& operator << (ostream& os, const pair<T,S>& p){return os << p.first << " " << p.second;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(size_t i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator   end(){ return range_iterator(  end_, step_); } };

  inline string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){ stringstream ss; for(size_t i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str(); }

  inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }
}
constexpr long long mod = 9_ten + 7;

int main(){
  int h,w;
  cin >> h,w;
  vector<string> a(h);
  cin >> a;

  deque<int> cnt(26, 0);
  for(int i=0; i<h; i++){
    for(auto c : a[i]){
      cnt[c-'a']++;
    }
  }

  vector<vector<int>> checked(h, vector<int>(w, 0));
  map<int,int> v;
  for(int i=0; i<h; i++){
    for(int j=0; j<w; j++){
      if(checked[i][j]) continue;
      int ii = h-1-i;
      int jj = w-1-j;
      int tmp = 0;
      for(auto y : {i,ii}) for(auto x : {j,jj}){
        if(!checked[y][x]){
          checked[y][x] = 1;
          tmp++;
        }
      }
      v[tmp]++;
    }
  }

  sort(cnt.begin(), cnt.end());

  if(v.count(1)){
    bool odd = false;
    for(int i=0; i<cnt.size(); i++){
      if( cnt[i] % 2 ){
        odd = true;
        cnt[i]--;
        break;
      }
    }
    if(!odd){
      println("No");
      return 0;
    }
  }

  while(cnt.size() && cnt.front() == 0) cnt.pop_front();
  priority_queue<int, vector<int>, less<int>> pq(cnt.begin(), cnt.end());

  while(v[4]){
    if(pq.size() && pq.top() >= 4){
      v[4] -= 1;
      int tmp = pq.top()-4;
      pq.pop();
      if(tmp) pq.push(tmp);
    }else{
      println("No");
      return 0;
    }
  }
  while(v[2]){
    if(pq.size() && pq.top() >= 2){
      v[2] -= 1;
      int tmp = pq.top()-2;
      pq.pop();
      if(tmp) pq.push(tmp);
    }else{
      println("No");
      return 0;
    }
  }

  if(pq.size()){
    println("No");
  }else{
    println("Yes");
  }

  return 0;
}


Measured memory_bytes: 256