Buggy python submission (verdict: Runtime Error):
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
alp=string.ascii_lowercase
d_al=dict([(i,j) for j,i in enumerate(alp)])

s=[d_al[i] for i in input()]
t=[d_al[i] for i in input()]
Ss=set(s)
St=set(t)
ns=len(s)
nt=len(t)
ss=s*2
#print(ss)

g=[{} for _ in range(ns)]
pos=[-1]*26
for i in range(ns*2)[::-1]:
    for j in Ss:
        if i<ns:
            g[i][j]=pos[j]-i
    pos[ss[i]]=i
#for i in range(len(g)):
#    print(g[i])

if len(St-Ss)!=0:
    ans=-1
else:
    cur=0
    ans=1+g[-1][t[0]]
    cur+=g[-1][t[0]]
    for i in range(1,nt):
        #print(cur,s[cur],'tg=',t[i],g[cur][t[i]])
        ans+=g[cur][t[i]]
        cur+=g[cur][t[i]]
        cur%=ns
print(ans)#,loop,has)


Fixed submission:
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
alp=string.ascii_lowercase
d_al=dict([(i,j) for j,i in enumerate(alp)])

s=[d_al[i] for i in input()]
t=[d_al[i] for i in input()]
Ss=set(s)
St=set(t)
ns=len(s)
nt=len(t)
ss=s*2
#print(ss)

g=[{} for _ in range(ns)]
pos=[-1]*26
for i in range(ns*2)[::-1]:
    for j in Ss:
        if i<ns:
            g[i][j]=pos[j]-i
    pos[ss[i]]=i
#for i in range(len(g)):
#    print(g[i])

if len(St-Ss)!=0:
    ans=-1
else:
    cur=0
    cur+=g[-1][t[0]]-1
    #print(cur)
    for i in range(1,nt):
        #print(cur,s[cur%ns],'tg=',t[i],g[cur%ns][t[i]])
        cur+=g[cur%ns][t[i]]
    ans=cur+1
print(ans)

Buggy python submission (verdict: Runtime Error):
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=[-1 for i in range(26)]
lp=[-1 for i in range(26)]

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


Fixed submission:
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
alp=string.ascii_lowercase
d_al=dict([(i,j) for j,i in enumerate(alp)])

s=[d_al[i] for i in input()]
t=[d_al[i] for i in input()]
Ss=set(s)
St=set(t)
ns=len(s)
nt=len(t)
ss=s*2
#print(ss)

g=[{} for _ in range(ns)]
pos=[-1]*26
for i in range(ns*2)[::-1]:
    for j in Ss:
        if i<ns:
            g[i][j]=pos[j]-i
    pos[ss[i]]=i
#for i in range(len(g)):
#    print(g[i])

if len(St-Ss)!=0:
    ans=-1
else:
    cur=0
    cur+=g[-1][t[0]]-1
    #print(cur)
    for i in range(1,nt):
        #print(cur,s[cur%ns],'tg=',t[i],g[cur%ns][t[i]])
        cur+=g[cur%ns][t[i]]
    ans=cur+1
print(ans)

Buggy python submission (verdict: Runtime Error):
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=[-1 for i in range(26)]
lp=[-1 for i in range(26)]

for i,c in enumerate(s):
    fp[di[c]]=i
    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],0)

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


#print(Ss,St,St-Ss)
if len(St-Ss)!=0:
    ans=-1
else:
    loop=0
    st=di[t[0]]
    i_n=g[0][st][0]
    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]))
'''

Fixed submission:
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
alp=string.ascii_lowercase
d_al=dict([(i,j) for j,i in enumerate(alp)])

s=[d_al[i] for i in input()]
t=[d_al[i] for i in input()]
Ss=set(s)
St=set(t)
ns=len(s)
nt=len(t)
ss=s*2
#print(ss)

g=[{} for _ in range(ns)]
pos=[-1]*26
for i in range(ns*2)[::-1]:
    for j in Ss:
        if i<ns:
            g[i][j]=pos[j]-i
    pos[ss[i]]=i
#for i in range(len(g)):
#    print(g[i])

if len(St-Ss)!=0:
    ans=-1
else:
    cur=0
    cur+=g[-1][t[0]]-1
    #print(cur)
    for i in range(1,nt):
        #print(cur,s[cur%ns],'tg=',t[i],g[cur%ns][t[i]])
        cur+=g[cur%ns][t[i]]
    ans=cur+1
print(ans)