#include <bits/stdc++.h>
#define MOD 998244353
using namespace std;
int main() {
int t;
cin >> t;
while (t--) {
int n;
cin >> n;
string a, b;
cin >> a >> b;
long long moves = 0;
for (int i = 0; i < n; i++) {
if (a[i] != b[i]) {
moves = (moves + 1LL * (MOD + 1) / 2) % MOD;
}
}
cout << moves << endl;
}
return 0;
}
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