#include <cstdio>
#include <cstring>
char s[100], t[100];
int main() {
  scanf("%s%s", s, t);
  int n = strlen(s), m = strlen(t);
  for (int i = 0; i <= n - m; ++i) {
    int j;
    for (j = 0; j < m; ++j)
      if (s[i + j] != t[j] && s[i + j] != '?') break;
    if (j >= m) {
      for (int j = 0; j < i; ++j) putchar((s[j] == '?') ? 'a' : s[j]);
      for (int j = 0; j < m; ++j) putchar(t[j]);
      for (int j = i + m; j < n; ++j) putchar((s[j] == '?') ? 'a' : s[j]);
      return 0;
    }
  }
  puts("UNRESTORABLE");
  return 0;
}