Language: C++

#include "bits/stdc++.h"
 
using namespace std;
using ll = long long;
const double pi = acos(-1);
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
REP(i, v.size()) { if (i)os << " "; os << v[i]; }return os;
}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
REP(i, v.size()) { if (i)os << endl; os << v[i]; }return os;
}
 
int main() {
	int h, w;
	int al[26];
	bool odd = false;
	bool odd2 = false;
	bool notfour = false;
	int evencount = 0;
 
	REP(i, 26) {
		al[i] = 0;
	}
 
	cin >> h >> w;
 
	REP(i, h) {
		string s;
 
		cin >> s;
 
		REP(j, w) {
			al[s[j] - 'a']++;
		}
	}
 
	REP(i, 26) {
		if (odd && al[i] % 2 == 1) {
			odd2 = true;
		}
 
		if (al[i] % 2 == 1) {
			odd = true;
		}
 
		if (al[i] % 4 != 0) {
			notfour = true;
		}
 
		if (al[i] % 2 == 0 && al[i] % 4 != 0) {
			evencount += al[i];
		}
	}
 
	if (h % 2 == 0 || w % 2 == 0) {
		if (odd) {
			cout << "No" << endl;
			return 0;
		}
	}
 
	if (h % 2 == 1 && w % 2 == 1) {
		if (!odd || odd2) {
			cout << "No" << endl;
			return 0;
		}
	}
 
	if (h % 2 == 0 && w % 2 == 0) {
		if (odd || notfour) {
			cout << "No" << endl;
			return 0;
		}
	}
 
	if (h % 2 == 0 && w % 2 == 1 && w != 1) {
		if (evencount > h) {
			cout << "No" << endl;
			return 0;
		}
	}
 
	if (h % 2 == 1 && w % 2 == 0 &&  h != 1) {
		if (evencount > w) {
			cout << "No" << endl;
			return 0;
		}
	}
 
	cout << "Yes" << endl;
}

Compiler output:
a.cc:2:1: error: extended character   is not valid in an identifier
    2 |  
      | ^
a.cc:19:1: error: extended character   is not valid in an identifier
   19 |  
      | ^
a.cc:27:1: error: extended character   is not valid in an identifier
   27 |  
      | ^
a.cc:31:1: error: extended character   is not valid in an identifier
   31 |  
      | ^
a.cc:33:1: error: extended character   is not valid in an identifier
   33 |  
      | ^
a.cc:36:1: error: extended character   is not valid in an identifier
   36 |  
      | ^
a.cc:38:1: error: extended character   is not valid in an identifier
   38 |  
      | ^
a.cc:43:1: error: extended character   is not valid in an identifier
   43 |  
      | ^
a.cc:48:1: error: extended character   is not valid in an identifier
   48 |  
      | ^
a.cc:52:1: error: extended character   is not valid in an identifier
   52 |  
      | ^
a.cc:56:1: error: extended character   is not valid in an identifier
   56 |  
      | ^
a.cc:61:1: error: extended character   is not valid in an identifier
   61 |  
      | ^
a.cc:68:1: error: extended character   is not valid in an identifier
   68 |  
      | ^
a.cc:75:1: error: extended character   is not valid in an identifier
   75 |  
      | ^
a.cc:82:1: error: extended character   is not valid in an identifier
   82 |  
      | ^
a.cc:89:1: error: extended character   is not valid in an identifier
   89 |  
      | ^
a.cc:96:1: error: extended character   is not valid in an identifier
   96 |  
      | ^
a.cc:2:1: error: '\U000000a0' does not name a type
    2 |  
      | ^
a.cc:13:22: error: 'ostream' does not name a type
   13 | template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
      |                      ^~~~~~~
a.cc:16:22: error: 'ostream' does not name a type
   16 | template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
      |                      ^~~~~~~
a.cc:19:1: error: '\U000000a0' does not name a type
   19 |  
      | ^