//#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")

#include <vector>
#include <algorithm>
#include <iostream>

#define ll long long
#define ld long double
#define F first
#define S second
#define pb push_back
#define mp make_pair

using namespace std;

const int maxn = 200005;

int p = 67;
int m = 1e9 + 87;
int h[maxn];
int st[maxn];

void hsh(string& s)
{
    h[0] = int(s[0]) - int('0') + 1;
    for(int i = 1; i < int(s.size()); i++)
    {
        h[i] = ((1ll * h[i - 1] * p) % m + int(s[i]) - int('0') + 1) % m;
    }
    return;
}

int gethash(int l, int r)
{
    int ans = h[r];
    if (l > 0) ans -= (1ll * h[l - 1] * st[r - l + 1]) % m;
    ans += m;
    ans %= m;
    return ans;
}

int main()
{
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    freopen("robot.in", "r", stdin);
    freopen("robot.out", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    st[0] = 1;
    for(int i = 1; i < maxn; i++)
        st[i] = (1ll * st[i - 1]) % m;
    int k;
    string s;
    cin >> k >> s;
    hsh(s);
    ll ans = 0;
    for(int i = 0; i + k - 1 < int(s.size()); i++)
    {
        int n = i;
        int H = gethash(n, n + k - 1);
        int c = 0;
        for(int j = n + k; ; j += k)
        {
            if (j + k - 1 >= int(s.size())) break;
            if (H == gethash(j, j + k - 1)) c++;
                else break;
            i += k;
        }
        ll t = (c * k);
        for(int j = n + k * (c + 1); j < int(s.size()); j++)
            if (s[n] == s[j]) {t++; i++; n++;}
                else break;
        ans += (t * (t + 1)) / 2;

    }
    cout << ans;
    return 0;
}