Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(1+i, N):
        #if j <= i:
        #    continue
        for k in range(1+j, N+1):
            #if k <= j:
            #    continue
            if not(j-i == k-j or S[i-1] == S[j-1] or S[i-1] == S[k-1] or S[k-1] == S[j-1]):
                ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(1+i, N):
        #if j <= i:
        #    continue
        for k in range(1+j, N+1):
            #if k <= j:
            #    continue
            if not(j-i == k-j or S[i-1] == S[j-1] or S[i-1] == S[k-1] or S[k-1] == S[j-1]):
                ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(1+i, N):
        if j <= i:
            continue
        for k in range(1+j, N+1):
            if k <= j:
                continue
            if not(j-i == k-j or S[i-1] == S[j-1] or S[i-1] == S[k-1] or S[k-1] == S[j-1]):
                ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(2, N):
        if j <= i:
            continue
        for k in range(3, N+1):
            if k <= j:
                continue
            if not(j-i == k-j or S[i-1] == S[j-1] or S[i-1] == S[k-1] or S[k-1] == S[j-1]):
                ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(2, N):
        if j <= i:
            continue
        for k in range(3, N+1):
            if k <= j:
                continue
            if j-i != k-j and S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(2, N):
        if j < i:
            continue
        for k in range(3, N+1):
            if k < j:
                continue
            if S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1] and j-i != k-j:
                    ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N-2):
    for j in range(2, N):
        if j < i:
            continue
        for k in range(3, N+1):
            if k < j:
                continue
            if j-i != k-j and S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                    ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N+1):
    for j in range(2, N+1):
        if j < i:
            continue
        for k in range(3, N+1):
            if k < j:
                continue
            if j-i != k-j and S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                    ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N+1):
    for j in range(1, N+1):
        if j < i:
            continue
        for k in range(1, N+1):
            if k < j:
                continue
            if j-i != k-j and S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                    ans+=1
print(ans)

Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N+1):
    for j in range(1, N+1):
        if j < i:
            continue
        for k in range(1, N+1):
            if k < j:
                continue
            if j-i != k-j:
                if S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                    ans+=1
print(ans)






Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = II()
S = input()

ans = 0
for i in range(1, N+1):
    for j in range(1, N+1):
        if j < i:
            continue
        for k in range(1, N+1):
            if k < j:
                continue
            if j-i != k-j:
                if S[i-1] != S[j-1] and S[i-1] != S[k-1] and S[k-1] != S[j-1]:
                    ans+=1
print(ans)






Fixed submission:
import sys
import math
from functools import reduce

# 入力を整数に変換して受け取る
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
# 入力全てを整数に変換したものの配列を受け取る
def LI(): return list(map(int, sys.stdin.readline().split()))
# 入力全てを整数に変換して1引いたものの配列を受け取る
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def SR(): return sys.stdin.readline().rstrip()

ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'
ascii_uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ascii_uppercase2 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ'

# リストを改行区切りで出力する
p2D = lambda x: print(*x, sep="\n")
p2E = lambda x: print(''.join(x))
p2S = lambda x: print(*x, sep=" ")

def gcd_list(numbers):
    return reduce(math.gcd, numbers)

N = int(input())
S = input()
ans = S.count("R") * S.count("G") * S.count("B")
for i in range(N-2):
  for j in range(i+1,N-1):
    k=2*j-i
    if k>=N:
      continue
    if S[i]!=S[j] and S[j]!=S[k] and S[k]!=S[i]:
      ans-=1
print(ans)