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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i)
    elif S[i] == "G":
        G.append(i)
    else:
        B.append(i)
        
ans = len(R) * len(G) * len(B)
for i in R:
    for j in G:
        if abs(j-i) % 2 == 1:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
        else:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            k3 = min(j, i) + abs(j-i)//2
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
            if S[k3] == "B":
                ans -= 1
            
print(ans)

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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i)
    elif S[i] == "G":
        G.append(i)
    else:
        B.append(i)
        
ans = len(R) * len(G) * len(B)
for i in R:
    for j in G:
        if abs(j-i) % 2 == 1:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
        else:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            k3 = min(j, i) + abs(j-i)//2
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
            if S[k3] == "B":
                ans -= 1
            
print(ans)

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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i+1)
    elif S[i] == "G":
        G.append(i+1)
    else:
        B.append(i+1)
        
ans = 0
for r in R:
    for g in G:
        for b in B:
            i = min(r, g, b)
            k = max(r, g, b)
            j = r+g+b-i-k
            if j-i != k-j:
                ans += 1

print(ans)

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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i)
    elif S[i] == "G":
        G.append(i)
    else:
        B.append(i)
        
ans = len(R) * len(G) * len(B)
for i in R:
    for j in G:
        if abs(j-i) % 2 == 1:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
        else:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            k3 = min(j, i) + abs(j-i)//2
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
            if S[k3] == "B":
                ans -= 1
            
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import itertools

N = int(input())
S = input()

ans = 0
num_list = [i for i in range(N)]
for v in itertools.combinations(num_list, 3):
    left_num = v[0]
    mid_num = v[1]
    right_num = v[2]
    if abs(left_num - mid_num) != abs(mid_num - right_num):
        if S[left_num] != S[mid_num] and S[mid_num] != S[right_num] and S[left_num] != S[right_num]:
            ans += 1
            
print(ans)


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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i)
    elif S[i] == "G":
        G.append(i)
    else:
        B.append(i)
        
ans = len(R) * len(G) * len(B)
for i in R:
    for j in G:
        if abs(j-i) % 2 == 1:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
        else:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            k3 = min(j, i) + abs(j-i)//2
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
            if S[k3] == "B":
                ans -= 1
            
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
import itertools

N = int(input())
S = input()

ans = 0
num_list = [i for i in range(N)]
for v in itertools.combinations(num_list, 3):
    left_num = v[0]
    mid_num = v[1]
    right_num = v[2]
    if abs(left_num - mid_num) != abs(mid_num - right_num):
        if S[left_num] != S[mid_num] and S[mid_num] != S[right_num] and S[left_num] != S[right_num]:
            ans += 1
            
print(ans)


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

R = []
G = []
B = []
for i in range(N):
    if S[i] == "R":
        R.append(i)
    elif S[i] == "G":
        G.append(i)
    else:
        B.append(i)
        
ans = len(R) * len(G) * len(B)
for i in R:
    for j in G:
        if abs(j-i) % 2 == 1:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
        else:
            k1 = min(j, i) - abs(j-i)
            k2 = max(j, i) + abs(j-i)
            k3 = min(j, i) + abs(j-i)//2
            if k1 >= 0:
                if S[k1] == "B":
                    ans -= 1
            if k2 <= N-1:
                if S[k2] == "B":
                    ans -= 1
            if S[k3] == "B":
                ans -= 1
            
print(ans)