#define DEBUG 1
#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using tll = tuple<ll, ll, ll>;
#define all(v) (v).begin(), (v).end()
#define for1(i, n) for (ll i = 0; i < (n); i++)
#define for2(i, m, n) for (ll i = (m); i < (n); i++)
#define for3(i, m, n, d) for (ll i = (m); i < (n); i += (d))
#define rfor2(i, m, n) for (ll i = (m); i > (n); i--)
#define rfor3(i, m, n, d) for (ll i = (m); i > (n); i += (d))
#define INF 1111111111111111111LL
#define MOD 1000000007LL  // 10**9 + 7
#if DEBUG
#define dump(...) dump_1(#__VA_ARGS__, __VA_ARGS__)
#else
#define dump(...)
#endif
template <class Head>
void dump_1(const char* str, Head&& h)
{
    cerr << str << ": " << h << endl;
}
template <class Head, class... Tail>
void dump_1(const char* str, Head&& h, Tail&&... t)
{
    while (*str != ',') {
        cerr << *str++;
    }
    cerr << ": " << h << " ";
    dump_1(str + 1, t...);
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& v)
{
    os << "(" << v.first << ", " << v.second << ")";
    return os;
}
template <typename T1, typename T2, typename T3>
ostream& operator<<(ostream& os, const tuple<T1, T2, T3>& v)
{
    os << "(" << get<0>(v) << ", " << get<1>(v) << ", " << get<2>(v) << ")";
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << " ";
        }
        os << *it;
    }
    return os;
}
template <typename T>
ostream& operator<<(ostream& os, const set<T>& v)
{
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << " ";
        }
        os << *it;
    }
    return os;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& os, const map<T1, T2>& v)
{
    os << "{";
    for (auto it = v.begin(); it != v.end(); it++) {
        if (it != v.begin()) {
            os << ", ";
        }
        os << it->first << ":" << it->second;
    }
    os << "}";
    return os;
}
void Yes(void) { cout << "Yes" << endl; }
void No(void) { cout << "No" << endl; }
void YES(void) { cout << "YES" << endl; }
void NO(void) { cout << "NO" << endl; }
template <typename T>
void chmax(T& a, const T& b)
{
    if (a < b) {
        a = b;
    }
}
template <typename T>
void chmin(T& a, const T& b)
{
    if (a > b) {
        a = b;
    }
}
template <typename T>
void vin(vector<T>& v, ll len)
{
    for1 (i, len) {
        cin >> v[i];
    }
}
template <typename T>
void print(const T& v)
{
    cout << v << endl;
}
//---------------------------------------------------------
vll calc_count(string& S)
{
    vll cnt(26, 0);
    for (char c : S) {
        ll i = c - 'a';
        cnt[i]++;
    }
    return cnt;
}

ll step[100010][26];

void solve()
{
    string S, T;
    cin >> S >> T;
    vll cs = calc_count(S);
    vll ct = calc_count(T);
    ll lenS = S.length();
    ll lenT = T.length();
    for1 (i, 26) {
        if (cs[i] == 0 && ct[i] > 0) {
            print(-1);
            return;
        }
    }
    vll lastpos(26, -1);

    rfor2 (i, lenS - 1, -1) {
        ll ci = S[i] - 'a';
        lastpos[ci] = i;
    }
    rfor2 (i, lenS - 1, -1) {
        ll ci = S[i] - 'a';
        for1 (j, 26) {
            ll dis;
            if (lastpos[j] == i) {
                dis = lenS;
            }
            else {
                dis = (lastpos[j] + lenS - i) % lenS;
            }
            step[i][j] = dis;
        }
        lastpos[ci] = i;
    }

    ll pos = 0;
    ll ans = 0;
    while (S[pos] != T[0]) {
        ++pos;
    }
    ans = pos + 1;
    for2 (i, 1, lenT) {
        ll ci = T[i] - 'a';
        ll delta = step[pos][ci];
        ans += delta;
        pos = (pos + delta) % lenS;
    }
    print(ans);
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    solve();
}


Measured memory_bytes: 20944