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 Python (3.4.3) (judge verdict: Accepted)


import sys
#input = sys.stdin.readline

S = list(input())
T = list(input())

alpha2num = lambda c: ord(c) - ord('a') 

alpha = [[] for _ in range(26)]
for i,s in enumerate(S):
    alpha[alpha2num(s)].append(i)

import bisect
tmp = -1
N = len(S)
base = 0
for t in T:
    a = alpha2num(t)
    if len(alpha[a]) == 0:
        print(-1)
        sys.exit()
    else:
        L = len(alpha[a])        
        num = bisect.bisect_right(alpha[a],tmp)
        
        if num == L:
            base += 1
            tmp = alpha[a][0]
        else:
            tmp = alpha[a][num]
ans = N * base + tmp + 1
print(ans)