Buggy python submission (verdict: Time Limit Exceeded):
# -*- coding: utf-8 -*-
# D

import sys
# 再起回数上限変更
# sys.setrecursionlimit(1000000)
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []


for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
    if s == 'G':
        G.append(idx+1)
    if s == 'B':
        B.append(idx+1)
# print(R, G, B)

if (len(R) > 0) and (len(G) > 0) and (len(B) > 0):
    pass
else:
    print(0)
    sys.exit()
    
R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        if s > G[-1]:
            break
        idx1 = bisect_left(G, s)
        for g in G[idx1:]:
            if g > B[-1]:
                break
            idx2 = bisect_left(B, g)
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)



Fixed submission:
# -*- coding: utf-8 -*-
# D

import sys
# 再起回数上限変更
# sys.setrecursionlimit(1000000)
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []

cnt_r, cnt_g, cnt_b = 0, 0, 0
for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
        cnt_r += 1
    if s == 'G':
        G.append(idx+1)
        cnt_g += 1
    if s == 'B':
        B.append(idx+1)
        cnt_b += 1
# print(R, G, B)

if (cnt_r > 0) and (cnt_g > 0) and (cnt_b > 0):
    pass
else:
    print(0)
    sys.exit()

R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        if s > G[-1]:
            break
        idx1 = bisect_left(G, s)
        for g in G[idx1:]:
            if g > B[-1]:
                break
            idx2 = bisect_left(B, g)
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)

Buggy python submission (verdict: Runtime Error):
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []

for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
    if s == 'G':
        G.append(idx+1)
    if s == 'B':
        B.append(idx+1)
# print(R, G, B)

R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        if s > G[-1]:
            break
        idx1 = bisect_left(G, s)
        for g in G[idx1:]:
            if g > B[-1]:
                break
            idx2 = bisect_left(B, g)
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)


Fixed submission:
# -*- coding: utf-8 -*-
# D

import sys
# 再起回数上限変更
# sys.setrecursionlimit(1000000)
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []

cnt_r, cnt_g, cnt_b = 0, 0, 0
for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
        cnt_r += 1
    if s == 'G':
        G.append(idx+1)
        cnt_g += 1
    if s == 'B':
        B.append(idx+1)
        cnt_b += 1
# print(R, G, B)

if (cnt_r > 0) and (cnt_g > 0) and (cnt_b > 0):
    pass
else:
    print(0)
    sys.exit()

R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        if s > G[-1]:
            break
        idx1 = bisect_left(G, s)
        for g in G[idx1:]:
            if g > B[-1]:
                break
            idx2 = bisect_left(B, g)
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)

Buggy python submission (verdict: Runtime Error):
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []

for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
    if s == 'G':
        G.append(idx+1)
    if s == 'B':
        B.append(idx+1)
# print(R, G, B)

R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        idx1 = bisect_left(G, s)
        if idx1 > G[-1]:
            break
        for g in G[idx1:]:
            idx2 = bisect_left(B, g)

            if idx2 > B[-1]:
                break
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)


Fixed submission:
# -*- coding: utf-8 -*-
# D

import sys
# 再起回数上限変更
# sys.setrecursionlimit(1000000)
from bisect import bisect_left

N = int(input())
S = input()
R = []
G = []
B = []

cnt_r, cnt_g, cnt_b = 0, 0, 0
for idx, s in enumerate(S):
    if s == 'R':
        R.append(idx+1)
        cnt_r += 1
    if s == 'G':
        G.append(idx+1)
        cnt_g += 1
    if s == 'B':
        B.append(idx+1)
        cnt_b += 1
# print(R, G, B)

if (cnt_r > 0) and (cnt_g > 0) and (cnt_b > 0):
    pass
else:
    print(0)
    sys.exit()

R0, G0, B0 = R, G, B

sum = 0

for i in range(6):
    if i == 0:
        R, G, B, temp = R0, G0, B0, 'B'
    elif i == 1:
        R, G, B, temp = R0, B0, G0, 'G'
    elif i == 2:
        R, G, B, temp = B0, R0, G0, 'G'
    elif i == 3:
        R, G, B, temp = B0, G0, R0, 'R'
    elif i == 4:
        R, G, B, temp = G0, R0, B0, 'B'
    elif i == 5:
        R, G, B, temp = G0, B0, R0, 'R'

    for s in R:
        if s > G[-1]:
            break
        idx1 = bisect_left(G, s)
        for g in G[idx1:]:
            if g > B[-1]:
                break
            idx2 = bisect_left(B, g)
            sum += len(B[idx2:])
            if 2 * g - s <= N:
                if S[2 * g - s - 1] == temp:
                    sum -= 1

print(sum)