#include<bits/stdc++.h>
using namespace std;

int n,m;

int cnt[30];

int f0,t1,t0;

int main(){
      cin>>n>>m;

      for(int i=0;i<n;i++)    {
            string in;
            cin>>in;
            for(int j=0;j<m;j++)    {
                  cnt[in[j]-'a']++;
            }
      }


      for(int i=0;i<26;i++)    {
            if(cnt[i]==0)    continue;
            if(cnt[i]%4!=0)    f0++;
            if(cnt[i]%4!=0 && cnt[i]%2==0)   t0++;
            else if(cnt[i]%2==1)   t1++;
      }


      bool b=0;

      if(m%2==1 && n%2==1)    {
            if(t1==1&&f0==1)    b=1;
            else if(t1==1&&t0==(m-1)/2+(n-1)/2)    b=1;
      }
      else if(m%2==0 && n%2==0)    {
            if(f0==0)    b=1;
      }
      else if(m%2==0)    {
            if(t1==0 && t0<=m/2)    b=1;
      }
      else    {
           if(t1==0 && t0<=n/2)    b=1;
      }

      if(b)    cout<<"Yes"<<endl;
      else    cout<<"No"<<endl;



      return 0;

}
