Buggy python submission (verdict: Time Limit Exceeded):
import itertools
import collections
N = int(input())
S = input()

result = 0
route = [x for _,x in collections.Counter(S).items()]

for i in range(1,len(route)+1):
    xxx = result
    for cb in itertools.combinations(route, i):
        num = 1
        for x in cb:
            num = num * x
        result += num
    if xxx == result:
        break
print(result%(10**9+7))


Fixed submission:
import collections
N = int(input())
S = input()

result = 1
route = [x+1 for _,x in collections.Counter(S).items()]
for x in route:
    result = result*x
print((result-1)%(10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
import itertools
N = int(input())
S = input()

result = 0
route = []
for x in set(S):
    co = S.count(x)
    if co > 0:
        route.append(co)

for i in range(1,len(route)+1):
    xxx = result
    for cb in itertools.combinations(route, i):
        num = 1
        for x in cb:
            num = num * x
        result += num
    if xxx == result:
        break
print(result%(10**9+7))


Fixed submission:
import collections
N = int(input())
S = input()

result = 1
route = [x+1 for _,x in collections.Counter(S).items()]
for x in route:
    result = result*x
print((result-1)%(10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
import itertools
N = int(input())
S = input()

result = 0
route = []
abc = set(list(S))
for x in abc:
    co = S.count(x)
    if co > 0:
        route.append(co)

for i in range(1,len(route)+1):
    xxx = result
    for cb in itertools.combinations(route, i):
        num = 1
        for x in cb:
            num = num * x
        result += num
    if xxx == result:
        break
print(result%(10**9+7))


Fixed submission:
import collections
N = int(input())
S = input()

result = 1
route = [x+1 for _,x in collections.Counter(S).items()]
for x in route:
    result = result*x
print((result-1)%(10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
import itertools
N = int(input())
S = input()

result = 0
route = []
abc = 'abcdefghijklmnopqrstuvwxyz'
for i in range(len(abc)):
    co = S.count(abc[i])
    if co > 0:
        route.append(co)

for i in range(1,len(route)+1):
    xxx = result
    #i種類取り出して掛け算した値を足し込む
    for cb in itertools.combinations(route, i):
        num = 1
        for x in cb:
            num = num * x
        result += num
    if xxx == result:
        break
print(result%(10**9+7))


Fixed submission:
import collections
N = int(input())
S = input()

result = 1
route = [x+1 for _,x in collections.Counter(S).items()]
for x in route:
    result = result*x
print((result-1)%(10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
import itertools
N = int(input())
S = input()

cache = {}
for i in range(N):
    if S[i] in cache:
        cache[S[i]].append(i)
    else:
        cache[S[i]] = [i]

result = 0
route = []
for k,v in cache.items():
    route.append(len(v))
for i in range(1,28):
    xxx = result
    #i種類取り出して掛け算した値を足し込む
    for cb in itertools.combinations(route, i):
        num = 1
        for x in cb:
            num = num * x
        result += num
    if xxx == result:
        break
print(result%(10**9+7))
            
        
            

Fixed submission:
import collections
N = int(input())
S = input()

result = 1
route = [x+1 for _,x in collections.Counter(S).items()]
for x in route:
    result = result*x
print((result-1)%(10**9+7))