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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            continue
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)

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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            continue
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)

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

Rs = 0
Gs = 0
Bs = 0
for i, il in enumerate(S):
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            continue
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)

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

Rs = []
Gs = []
Bs = []
for i, il in enumerate(S):
    if il == 'R':
        Rs.append(i)
    if il == 'G':
        Gs.append(i)
    if il == 'B':
        Bs.append(i)
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            continue
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(len(Rs)*len(Gs)*len(Bs) - num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)

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

Rs = []
Gs = []
Bs = []
for i, il in enumerate(S):
    if il == 'R':
        Rs.append(i)
    if il == 'G':
        Gs.append(i)
    if il == 'B':
        Bs.append(i)
num = 0
for i in Rs:
    for j in Gs:
        for k in Bs:
            if (2*i - j - k)*(2*j - k - i)*(2*k - i - j):
                num += 1
print(num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)

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

Rs = []
Gs = []
Bs = []
for i, il in enumerate(S):
    if il == 'R':
        Rs.append(i)
    if il == 'G':
        Gs.append(i)
    if il == 'B':
        Bs.append(i)
num = 0
for i in Rs:
    for j in Gs:
        for k in Bs:
            ijk = sorted([i, j, k])
            if (ijk[2] - ijk[1]) != (ijk[1] - ijk[0]):
                num += 1
print(num)


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

Rs = 0
Gs = 0
Bs = 0
for il in S:
    if il == 'R':
        Rs += 1
    if il == 'G':
        Gs += 1
    if il == 'B':
        Bs += 1
num = 0
for i in range(N):
    for step in range(1, N):
        j = i + step
        k = i + 2*step
        if k > N - 1:
            break
        if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
            num += 1
print(Rs*Gs*Bs - num)