#include <bits/stdc++.h>
using namespace std;
inline long long gcd(long long n1, long long n2) {
  return n2 == 0 ? abs(n1) : gcd(n2, n1 % n2);
}
inline long long lcm(long long n1, long long n2) {
  return n1 == 0 || n2 == 0 ? 0 : abs(n1 * (n2 / gcd(n1, n2)));
}
const int INF = 1000000000;
const int MAXN = 1000006;
int mat[MAXN][30];
int mark[MAXN];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n, m;
  while (cin >> n >> m) {
    string s1, s2;
    cin >> s1 >> s2;
    long long t1 = (int)s1.size(), t2 = (int)s2.size();
    long long x = gcd(t1, t2);
    memset(mark, 0, sizeof mark);
    memset(mat, 0, sizeof mat);
    for (int i = 0; i < t1; ++i) mat[i % x][s1[i] - 'a']++;
    long long res = 0LL;
    for (int i = 0; i < t2; ++i) res += (t1 / x) - mat[i % x][s2[i] - 'a'];
    res *= (t1 * n) / lcm(t1, t2);
    cout << res << endl;
  }
}
