#include 
     
      #include 
      
       #include 
       
        using namespace std;char src[5000 + 5];char dest[5000 + 5];int abs(int a) {  return a < 0 ? -a : a;}void solve() {  int i = -1;  int j = -1;  int ans = 0;  while (1) {    while (1) {      ++i;      if (src[i] == '\0' || src[i] == '+') break;    }    while (1) {      ++j;      if (dest[j] == '\0' || dest[j] == '+') break;    }    if (src[i] != dest[j]) {      ans = -1;      break;    }    ans = ans + abs(j - i);    if (src[i] == '\0') break;  }  printf("%d\n", ans);}int main() {  scanf("%s", src);  scanf("%s", dest);  solve();  return 0;}