Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	# t = min(ssb)

	cnt = 0

	for i in ipl:
		for j in ssb:
			if i == j:
				cnt += 1
			if i < j:
				break

print(cnt)

Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)

	cnt = 0

	for i in ipl:
		for j in ssb:
			if i == j:
				cnt += 1
			if i < j:
				break

print(cnt)

Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)

	cnt = 0

	for i in pl:
		for j in ssb:
			if i == j:
				cnt += 1
			if i < j:
				break

print(cnt)

Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 9999999999999
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)
	



Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	tl = [0] * max(ipl)
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)
	



Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	tl = [0] * max(ipl)
	for i in ssb:
		tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		cnt += tl[int(i)-1]

	print(cnt)
	



Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 1:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	ssb = sorted(sb)
	t = min(ssb)
	tl = [0] * max(pl)
	for i in ssb:
		tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		cnt += tl[int(i)-1]

	print(cnt)
	



Fixed submission:
n = int(input())
a = input().split()
pl = []
sb = []
for i in range(len(a)):
	pl.append(i+int(a[i])+1)
	if i - int(a[i]) > 0:
		sb.append(i-int(a[i])+1)


if len(sb) == 0:
	print('0')
else:

# spl = sorted(pl)
	isb = [int(i) for i in sb]
	ipl = [int(i) for i in pl]
	ssb = sorted(isb)
	t = min(ssb)
	# tl = [0] * max(ipl)
	tl = [0] * 2000000	
	for i in ssb:
		if int(i)-1 < len(tl):
			tl[int(i)-1] += 1
	# print(pl)
	# print(sb)
	# print(tl)
	cnt = 0
	for i in pl:
		if int(i)-1 < len(tl):
			cnt += tl[int(i)-1]

	print(cnt)