### BUGGY CODE ###

import sys
import numpy as np
import numba
from numba import njit, b1, i4, i8, f8

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

MASK30 = (1 << 30) - 1
MASK31 = (1 << 31) - 1
MASK61 = (1 << 61) - 1

@njit((i8, ), cache=True)
def rh_modulo(x):
    xu, xd = x >> 61, x & MASK61
    x = xu + xd
    if x >= MASK61:
        x -= MASK61
    return x


@njit((i8, i8), cache=True)
def rh_multiply(a, b):
    au, ad = a >> 31, a & MASK31
    bu, bd = b >> 31, b & MASK31
    x = ad * bu + au * bd
    xu, xd = x >> 30, x & MASK30
    return rh_modulo(au * bu * 2 + xu + (xd << 31) + ad * bd)


@njit((i8, i8), cache=True)
def rh_pows(base, max_len):
    pows = np.empty(max_len, np.int64)
    pows[0] = 1
    for n in range(1, max_len):
        pows[n] = rh_multiply(pows[n - 1], base)
    return pows


@njit((i8[:], i8, i8[:]), cache=True)
def compute_rh(pows, base, S):
    N = len(S)
    RH = np.empty(N, np.int64)
    RH[0] = S[0] + 10
    for n in range(1, N):
        x = rh_multiply(RH[n - 1], base) + S[n] + 10
        if x >= MASK61:
            x -= MASK61
        RH[n] = x
    return RH


@njit((i8[:], i8, i8[:], i8, i8), cache=True)
def rh_substr(pows, base, RH, l, r):
    h = RH[r]
    if l > 0:
        h -= rh_multiply(RH[l], pows[r - l])
    if h < 0:
        h += MASK61
    return h

@njit((i8[:], ), cache=True)
def main(S):
    S = S.copy()
    l_ind = np.where(S == -1)[0][:-1] + 1
    r_ind = np.where(S == -1)[0][1:]
    N = len(l_ind)
    # 逆順にしておく
    for i in range(N):
        S[l_ind[i]:r_ind[i]] = S[l_ind[i]:r_ind[i]][::-1]

    # rolling hashの計算
    max_len = len(S) + 10
    base = np.random.randint(0, 1 << 31)
    pows = rh_pows(base, max_len)
    RH = np.zeros_like(S)
    for i in range(N):
        RH[l_ind[i]:r_ind[i]] = compute_rh(pows, base, S[l_ind[i]:r_ind[i]])

    # 後ろ（自身も含む）に置ける文字集合の計算
    sets = np.zeros_like(S)
    for i in range(N):
        for j in range(r_ind[i] - 1, l_ind[i] - 1, -1):
            sets[j] = sets[j + 1] | 1 << S[j]

    # 作れる組 (prefix, 右からの1文字)をすべて計算する
    ptr = 0
    nums = dict()
    for i in range(N):
        for j in range(l_ind[i], r_ind[i]):
            for k in range(26):
                if sets[j] & 1 << k:
                    h = rh_multiply(RH[j - 1], base) + k
                    if h in nums:
                        nums[h] += 1
                    else:
                        nums[h] = 1
    # 各文字列とマッチングする対象を数える
    ans = 0
    for i in range(N):
        h = rh_multiply(RH[r_ind[i] - 2], base) + S[r_ind[i] - 1]
        ans += nums[h] - 1
    print(ans)

N = int(readline())
S = np.array(list(read().rstrip()), np.int64)

S[S == ord('\n')] = -1
S[S > 0] -= ord('a')
S = np.insert(S, 0, -1)
S = np.append(S, -1)

main(S)

### FIXED CODE ###

import sys
import numpy as np
import numba
from numba import njit, b1, i4, i8, f8

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

MASK30 = (1 << 30) - 1
MASK31 = (1 << 31) - 1
MASK61 = (1 << 61) - 1

@njit((i8, ), cache=True)
def rh_modulo(x):
    xu, xd = x >> 61, x & MASK61
    x = xu + xd
    if x >= MASK61:
        x -= MASK61
    return x


@njit((i8, i8), cache=True)
def rh_multiply(a, b):
    au, ad = a >> 31, a & MASK31
    bu, bd = b >> 31, b & MASK31
    x = ad * bu + au * bd
    xu, xd = x >> 30, x & MASK30
    return rh_modulo(au * bu * 2 + xu + (xd << 31) + ad * bd)


@njit((i8, i8), cache=True)
def rh_pows(base, max_len):
    pows = np.empty(max_len, np.int64)
    pows[0] = 1
    for n in range(1, max_len):
        pows[n] = rh_multiply(pows[n - 1], base)
    return pows


@njit((i8[:], i8, i8[:]), cache=True)
def compute_rh(pows, base, S):
    N = len(S)
    RH = np.empty(N, np.int64)
    RH[0] = S[0] + 10
    for n in range(1, N):
        x = rh_multiply(RH[n - 1], base) + S[n] + 10
        if x >= MASK61:
            x -= MASK61
        RH[n] = x
    return RH


@njit((i8[:], i8, i8[:], i8, i8), cache=True)
def rh_substr(pows, base, RH, l, r):
    h = RH[r]
    if l > 0:
        h -= rh_multiply(RH[l], pows[r - l])
    if h < 0:
        h += MASK61
    return h

@njit((i8[:], ), cache=True)
def main(S):
    S = S.copy()
    l_ind = np.where(S == -1)[0][:-1] + 1
    r_ind = np.where(S == -1)[0][1:]
    N = len(l_ind)
    # 逆順にしておく
    for i in range(N):
        S[l_ind[i]:r_ind[i]] = S[l_ind[i]:r_ind[i]][::-1]

    # rolling hashの計算
    max_len = len(S) + 10
    base = np.random.randint(0, 1 << 31)
    pows = rh_pows(base, max_len)
    RH = np.zeros_like(S)
    for i in range(N):
        RH[l_ind[i]:r_ind[i]] = compute_rh(pows, base, S[l_ind[i]:r_ind[i]])

    # 後ろ（自身も含む）に置ける文字集合の計算
    sets = np.zeros_like(S)
    for i in range(N):
        for j in range(r_ind[i] - 1, l_ind[i] - 1, -1):
            sets[j] = sets[j + 1] | 1 << S[j]

    # 作れる組 (prefix, 右からの1文字)をすべて計算する
    ptr = 0
    nums = np.empty(len(S) * 26 + 10, np.int64)
    for i in range(N):
        for j in range(l_ind[i], r_ind[i]):
            for k in range(26):
                if sets[j] & 1 << k:
                    h = rh_multiply(RH[j - 1], base) + k
                    nums[ptr] = h
                    ptr += 1
    nums = nums[:ptr]
    nums.sort()
    # 各文字列とマッチングする対象を数える
    ans = 0
    for i in range(N):
        h = rh_multiply(RH[r_ind[i] - 2], base) + S[r_ind[i] - 1]
        cnt = np.searchsorted(nums, h, 'right')
        cnt -= np.searchsorted(nums, h, 'left')
        ans += cnt - 1  # 自分を除外
    print(ans)

N = int(readline())
S = np.array(list(read().rstrip()), np.int64)

S[S == ord('\n')] = -1
S[S > 0] -= ord('a')
S = np.insert(S, 0, -1)
S = np.append(S, -1)

main(S)