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#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using pi = pair<int, int>;
using vpi = vector<pi>;
using vi = vector<int>;
using vll = vector<long long>;
using mpii = map<int, int>;
using mpll = map<ll, ll>;
using db = long double;
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define lb lower_bound
#define ub upper_bound
const int MOD = (int)1e9 + 7;
const db PI = acos((db)-1);
const int dx[4]{1, 0, -1, 0};
const int dy[4]{0, 1, 0, -1};
//pretty printing
template<typename K, typename V>
void printm(const map<K, V> &mp) {
cerr << "{" << endl;
for (auto p : mp) {
cerr << " { " << p.first << " : " << p.second << " }\n";
}
cerr << "}" << endl;
}
template<typename T>
void printv(const vector<T> &v) {
cerr << "[";
for (int i = 0; i < v.size(); i++) {
if (i == v.size() - 1) {
cerr << v[i];
} else {
cerr << v[i] << ", ";
}
}
cerr << "]\n";
}
template<typename T>
void printvv(const vector<vector<T>> &v) {
cerr << "[\n";
for (auto &vec : v) {
cout << " ";
printv(vec);
}
cerr << "]\n";
}
void print() {
cerr << "\n";
}
template<typename T, typename... TS>
void print(T val, TS... vals) {
cerr << val << " ";
print(vals...);
}
/* stuff you should look for:
---------------------------
* special cases (n=1?)
* int overflow, array bounds
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
*/
// dddaddd
// abcba
// dcaaacd
void solve() {
int n, m;
cin >> n >> m;
string a, b;
cin >> a >> b;
set<char> st;
string ab = a + b;
vector<int> fq('z' - 'a' + 2);
for(auto ch : ab) {
st.insert(ch);
fq[ch - 'a']++;
}
int even = 0;
int odd = 0;
if ((n + m) % 2 == 0) {
for (auto ch : st) {
even += fq[ch - 'a'] % 2 == 0;
}
cout << (even == st.size() ? "YES" : "NO") << '\n';
} else {
char cho;
for (auto ch : st) {
even += fq[ch - 'a'] % 2 == 0;
if (fq[ch - 'a'] % 2 != 0) {
odd += fq[ch - 'a'] % 2 != 0;
cho = ch;
}
}
if (odd == 1) {
if (n > m) {
cout << (count(all(a), cho) ? "YES" : "NO") << '\n';
} else {
cout << (count(all(b), cho) ? "YES" : "NO") << '\n';
}
} else {
cout << "NO" << '\n';
}
}
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int tt;
cin >> tt;
while(tt--) {
solve();
}
}
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