#include <bits/stdc++.h>
using namespace std;
const int maxn = 4005;
int f[maxn][maxn], prea[maxn][26], preb[maxn][26];
char a[maxn], b[maxn];
int n, m, ti, td, tr, te;
int main() {
  int i, j, x, y;
  scanf("%d%d%d%d", &ti, &td, &tr, &te);
  scanf("%s%s", a + 1, b + 1);
  n = strlen(a + 1);
  m = strlen(b + 1);
  for (i = 1; i <= n; ++i) {
    memcpy(prea[i], prea[i - 1], sizeof prea[0]);
    prea[i][a[i] - 'a'] = i;
    f[i][0] = i * td;
  }
  for (i = 1; i <= m; ++i) {
    memcpy(preb[i], preb[i - 1], sizeof preb[0]);
    preb[i][b[i] - 'a'] = i;
    f[0][i] = i * ti;
  }
  for (i = 1; i <= n; ++i)
    for (j = 1; j <= m; ++j) {
      f[i][j] = min(f[i - 1][j] + td, f[i][j - 1] + ti);
      f[i][j] = min(f[i][j], f[i - 1][j - 1] + (a[i] != b[j] ? tr : 0));
      x = prea[i - 1][b[j] - 'a'];
      y = preb[j - 1][a[i] - 'a'];
      if (x && y)
        f[i][j] = min(f[i][j], f[x - 1][y - 1] + te + (i - x - 1) * td +
                                   (j - y - 1) * ti);
    }
  printf("%d\n", f[n][m]);
  return 0;
}
