Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Fixed submission:
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
S = input()
ans = 0
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += S[j+1:].count('R')
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += S[j+1:].count('G')
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += S[j+1:].count('B')
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Fixed submission:
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
S = input()
ans = 0
lista = [[[0 for i in range(N)] for j in range(N)] for k in range(3)]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        if a != S[j]:
            if a != 'R' and S[j] != 'R':
                lista[0][j-i][j] += 1
            elif a != 'G' and S[j] != 'G':
                lista[1][j-i][j] += 1
            elif a != 'B' and S[j] != 'B':
                lista[2][j-i][j] += 1
for k in range(2,N):
    for j in range(k):
        if S[k] == 'R':
            ans += sum(lista[0][j][:k]) - lista[0][j][k-j]
        if S[k] == 'G':
            ans += sum(lista[1][j][:k]) - lista[1][j][k-j]
        if S[k] == 'B':
            ans += sum(lista[2][j][:k]) - lista[2][j][k-j]
print(ans)

Fixed submission:
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
S = input()
ans = 0
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            for k in range(j+1,N):
                if a != S[k] and b != S[k] and j-i != k-j:
                    ans += 1
print(ans)

Fixed submission:
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
S = input()
ans = 0
for i in range(N-2):
    for j in range(i+1,N-1):
        if S[i] != S[j]:
            for k in range(j+1,N):
                if S[i] != S[k] and S[j] != S[k] and j-i != k-j:
                    ans += 1
print(ans)
            

Fixed submission:
N = int(input())
S = input()
ans = 0
count = [[0 for i in range(N)] for j in range(3)]
for i in range(N):
    if S[i] == 'R':
        count[0][i] = 1
    if S[i] == 'G':
        count[1][i] = 1
    if S[i] == 'B':
        count[2][i] = 1
for i in range(3):
    for j in range(N-1,0,-1):
        count[i][j-1] += count[i][j]
for i in range(N-2):
    a = S[i]
    for j in range(i+1,N-1):
        b = S[j]
        if a != b:
            if a != 'R' and b != 'R':
                ans += count[0][j]
                if 2*j-i < N and S[j+j-i] == 'R':
                    ans -= 1
            if a != 'G' and b != 'G':
                ans += count[1][j]
                if 2*j-i < N and S[j+j-i] == 'G':
                    ans -= 1
            if a != 'B' and b != 'B':
                ans += count[2][j]
                if 2*j-i < N and S[j+j-i] == 'B':
                    ans -= 1
print(ans)