Problem:
Score : 500 points

Problem Statement

Given are two strings s and t consisting of lowercase English letters. Determine if there exists an integer i satisfying the following condition, and find the minimum such i if it exists.

Let s' be the concatenation of 10^{100} copies of s. t is a subsequence of the string {s'}_1{s'}_2\ldots{s'}_i (the first i characters in s').

Notes

A subsequence of a string a is a string obtained by deleting zero or more characters from a and concatenating the remaining characters without changing the relative order. For example, the subsequences of contest include net, c, and contest.

Constraints

1 \leq |s| \leq 10^5

1 \leq |t| \leq 10^5

s and t consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s
t

Output

If there exists an integer i satisfying the following condition, print the minimum such i; otherwise, print -1.

Sample Input 1

contest
son

Sample Output 1

10

t = son is a subsequence of the string contestcon (the first 10 characters in s' = contestcontestcontest...), so i = 10 satisfies the condition.

On the other hand, t is not a subsequence of the string contestco (the first 9 characters in s'), so i = 9 does not satisfy the condition.

Similarly, any integer less than 9 does not satisfy the condition, either. Thus, the minimum integer i satisfying the condition is 10.

Sample Input 2

contest
programming

Sample Output 2

-1

t = programming is not a substring of s' = contestcontestcontest.... Thus, there is no integer i satisfying the condition.

Sample Input 3

contest
sentence

Sample Output 3

33

Note that the answer may not fit into a 32-bit integer type, though we cannot put such a case here.

Solution in PyPy3 (2.4.0) (judge verdict: Accepted)

#!/usr/bin/env python3
from collections import defaultdict,deque
from heapq import heappush, heappop
from bisect import bisect_left, bisect_right
import sys, random, itertools, math
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
sqrt = math.sqrt
def LI(): return list(map(int, input().split()))
def LF(): return list(map(float, input().split()))
def LI_(): return list(map(lambda x: int(x)-1, input().split()))
def II(): return int(input())
def IF(): return float(input())
def LS(): return list(map(list, input().split()))
def S(): return list(input().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')

#A
def A():
    d = {"Sunny":1 , "Cloudy":2, "Rainy":0}
    a = ["Sunny", "Cloudy", "Rainy"]
    print(a[d[input().rstrip()]])
    return

#B
def B():
    s = S()
    for i, si in enumerate(s):
        if i % 2:
            if si == "R":
                print("No")
                return
        else:
            if si == "L":
                print("No")
                return
    print("Yes")
    return

#C
def C():
    n, k, q = LI()
    d = [0] * n
    for _ in range(q):
        a = II() - 1
        d[a] += 1
    for a in d:
        if k - (q - a) > 0:
            print("Yes")
        else:
            print("No")
    return

#D
def D():
    n,m = LI()
    a = LI()
    q = []
    for ai in a:
        heappush(q, -ai)
    for _ in range(m):
        heappush(q, heappop(q) / 2)
    ans = 0
    while q:
        ans += int(-heappop(q))
    print(ans)
    return

#E
def E():
    s = S()
    t = S()
    d = defaultdict(list)
    for i,si in enumerate(s):
        d[si].append(i)
    if d[t[0]] == []:
        print(-1)
        return
    before = d[t[0]][0]
    ans = 0
    for ti in t[1:]:
        if d[ti] == []:
            print(-1)
            return
        a = d[ti]
        index = bisect_right(a, before)
        if index == len(a):
            ans += 1
            before = a[0]
        else:
            before = a[index]
    print(ans * len(s) + before + 1)
    return

#F
def F():
    return

#Solve
if __name__ == '__main__':
    E()