#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1000000;
struct UnionFind {
  int par[MAX_N], ra[MAX_N];
  void init(int n) {
    for (int(i) = 0; (i) < (n); (i)++) par[i] = i, ra[i] = 0;
  }
  int find(int x) { return par[x] == x ? x : par[x] = find(par[x]); }
  bool same(int x, int y) { return find(x) == find(y); }
  void unite(int x, int y) {
    if ((x = find(x)) != (y = find(y))) {
      if (ra[x] < ra[y]) swap(x, y);
      par[y] = x, ra[x] += (ra[x] == ra[y]);
    }
  }
};
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long A, B;
string a, b;
int pp[1000000][26];
int sz[1000000];
UnionFind uf;
int main() {
  scanf("%I64d%I64d", &A, &B);
  cin >> a >> b;
  long long al = a.size(), bl = b.size();
  long long st = al * bl;
  st /= gcd(al, bl);
  uf.init(al);
  for (int(i) = 0; (i) < (al); (i)++) uf.unite(i, (i + bl) % al);
  for (int(i) = 0; (i) < (al); (i)++) {
    int ns = uf.find(i);
    pp[ns][a[i] - 'a']++;
    sz[ns]++;
  }
  long long ans = 0;
  for (int(i) = 0; (i) < (bl); (i)++) {
    int ns = uf.find(i % al);
    for (int(j) = 0; (j) < (26); (j)++)
      if (j != b[i] - 'a') ans += pp[ns][j];
  }
  long long kkd = A * al / st;
  cout << ans * kkd << endl;
}
