program main
  implicit none
  integer::H,W
  integer::AZ(26)=0
  character(100)::a
  integer::t(3)
  integer::i,j
  read*,H,W
  do i=1,H
    read*,A
    do j=1,W
      AZ(ichar(A(j:j))-ichar("a")+1)=AZ(ichar(A(j:j))-ichar("a")+1)+1
    end do
  end do
  t(1)=merge(1,0,mod(H,2)*mod(W,2)==1)
  t(2)=mod(H,2)*(W/2)+mod(W,2)*(H/2)
  t(3)=(W/2)*(H/2)
  do i=1,t(3)
    do j=1,26
      if(AZ(j)>=4)then
        AZ(j)=AZ(j)-4
        exit
      endif
    end do
  end do
  do i=1,t(2)
    do j=1,26
      if(AZ(j)>=2)then
        AZ(j)=AZ(j)-2
        exit
      endif
    end do
  end do
  do i=1,t(1)
    do j=1,26
      if(AZ(j)>=1)then
        AZ(j)=AZ(j)-1
        exit
      endif
    end do
  end do
  print"(A)",trim(merge("Yes","No ",maxval(AZ)==0))
end program main