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)

from heapq import heappush, heappop
from collections import deque,defaultdict,Counter
import itertools
from itertools import permutations
import sys
import bisect
import string
sys.setrecursionlimit(10**6)
def SI():
    return input().split()
def MI():
    return map(int,input().split())
def I():
    return int(input())
def LI():
    return [int(i) for i in input().split()]
YN=['Yes','No']
mo=10**9+7

s=input()
t=input()
s=list(s)
t=list(t)
Ss=set(s)
St=set(t)
n=len(s)

alp=string.ascii_lowercase
di=dict([(i,j) for j,i in enumerate(alp)])
#print(di)
g=[{} for _ in range(n)]
fp=[10*10 for i in range(26)]
lp=[-1 for i in range(26)]

for i,c in enumerate(s):
    fp[di[c]]=min(i,fp[di[c]])
    for next_c in [di[l] for l in Ss]:
        if fp[next_c]!=-1:
            g[i][next_c]=(fp[next_c],1)

for i in range(n)[::-1]:
    lp[di[s[i]]]=i
    for next_c in [di[l] for l in Ss]:
        if lp[next_c]!=-1:
            g[i][next_c]=(lp[next_c],1 if i==lp[next_c] else 0)

m=[[] for i in range(n)]


#print(Ss,St,St-Ss)
if len(St-Ss)!=0:
    ans=-1
else:
    loop=0
    has=0
    st=di[t[0]]
    loop+=g[0][st][1]
    i_n=g[0][st][0]
    has=i_n
    for i in range(1,len(t)):
        ch=di[t[i]]
        loop+=g[i_n][ch][1]
        i_n=g[i_n][ch][0]
        has=g[i_n][ch][0]
        #print(loop,has,i_n,g[i_n][ch])
    ans=loop*n+has+1
print(ans)#,loop,has)
#print([[i,di[i]] for i in s])
'''
for i in g:
    print(sorted(list(i.items()),key=lambda x:x[0]))
'''