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: Wrong Answer)

import sys
sys.setrecursionlimit(10**9)
INF=10**18
def input():
    return sys.stdin.readline().rstrip()

def main():
    a=ord('a')
    s=list(map(lambda x:ord(x)-a,input()))
    N=len(s)
    t=list(map(lambda x:ord(x)-a,input()))
    l=[[-1]*26 for _ in range(len(s))]
    for i in range(N-1,-N,-1):
        for j in range(26):
            if l[i-1]!=-1:
                if s[i]==j:
                    l[i-1][j]=i
                else:
                    l[i-1][j]=l[i][j]
    ans=0
    index=N-1
    for a in t:
        n=l[index][a]
        if n==-1:
            print(-1)
            exit()
        if n>index:
            ans+=n-index
        else:
            ans+=n+N-index
        index=n
    print(ans)

if __name__ == '__main__':
    main()