using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using static System.Console;
using static System.Math;
using static MyIO;
using static MyUtil;

public class E { public static void Main() => (new Solver()).Solve(); }

public class Solver
{
	public void Solve()
	{
		var s = GetString().Select(x => (long)(x - 'a')).ToArray();
		var t = GetString().Select(x => (long)(x - 'a')).ToArray();
		long N = s.Length;

		var list = Range(0, 26).Select(_ => new List<long>()).ToArray();
		for(long i = 0; i < 2 * N; i++)
			list[s[i % N]].Add(i);

		long binarySearch(long pos, long c)
		{
			long ng = -1;
			long ok = list[c].Count;
			while(Abs(ok - ng) > 1)
			{
				long mid = (ng + ok) / 2;
				if(list[c][(int)mid] > pos)
					ok = mid;
				else
					ng = mid;
			}
			return ok;
		}

		long INF = long.MaxValue / 2;
		var cost = new long[N, 26];
		for(long i = 0; i < N; i++)
		{
			for(long j = 0; j < 26; j++)
			{
				long bs = binarySearch(i, j);
				cost[i, j] = (bs == list[j].Count) ? INF : list[j][(int)bs] - i;				
			}
		}

		long head = Array.FindIndex(s, x => x == t[0]);
		if(head == -1)
		{
			WriteLine(-1);
			return;
		}

		long cnt = head + 1;
		long pos = head;
		for(long i = 1; i < t.Length; i++)
		{
			if(cost[pos, t[i]] == INF)
			{
				WriteLine(-1);
				return;
			}
			cnt += cost[pos, t[i]];
			pos = (pos + cost[pos, t[i]]) % N;
		}
		WriteLine(cnt);
	}
}

public static class MyIO
{
	private static string[] args = new string[0];
	private static int cnt = 0;
	private static IEnumerable<string> getArgs(long N) => Range(0, N).Select(_ => getArg());
	private static string getArg()
	{
		if(cnt == args.Length) { args = Console.ReadLine().Split(); cnt = 0; }
		return args[cnt++];
	}

	public static int GetInt() => int.Parse(getArg());
	public static long GetLong() => long.Parse(getArg());
	public static double GetDouble() => double.Parse(getArg());
	public static decimal GetDecimal() => decimal.Parse(getArg());
	public static string GetString() => getArg();
	public static char GetChar() => getArg()[0];
	public static int[] GetInts(long N) => getArgs(N).Select(int.Parse).ToArray();
	public static long[] GetLongs(long N) => getArgs(N).Select(long.Parse).ToArray();
	public static double[] GetDoubles(long N) => getArgs(N).Select(double.Parse).ToArray();
	public static decimal[] GetDecimals(long N) => getArgs(N).Select(decimal.Parse).ToArray();
	public static string[] GetStrings(long N) => getArgs(N).ToArray();
}

public static class MyUtil
{
	public static void chmax<T>(ref T x, T y) where T : IComparable<T> { if(x.CompareTo(y) < 0) x = y; }
	public static void chmin<T>(ref T x, T y) where T : IComparable<T> { if(x.CompareTo(y) > 0)	x = y; }
	public static void swap<T>(ref T x, ref T y) { T tmp = x; x = y; y = tmp; }
	public static long rightShift(long x, long y) => (x >> (int)y);
	public static long leftShift(long x, long y) => (x << (int)y);
	public static bool contains(long s, long x) => (rightShift(s, x) & 1L) == 1L;
	public static long gcd(long x, long y) => (y == 0) ? x : gcd(y, x % y);
	public static long lcm(long x, long y) => (x / gcd(x,y)) * y;	
	public static IEnumerable<int> Range(long start, long count) => Enumerable.Range((int)start, (int)count);
	public static void Sort(this List<string> source) => source.Sort(StringComparer.Ordinal);
}


Measured memory_bytes: 56024