#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
const int MAXN = 5e5 + 5;
const ull B = 131;

ull h1[MAXN], h2[MAXN], p[MAXN];
int n;
char s[MAXN];

ull get1(int l, int r) {
    return h1[r] - h1[l-1] * p[r-l+1];
}

ull get2(int l, int r) {
    return h2[l] - h2[r+1] * p[r-l+1];
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n >> s+1;

    p[0] = 1;
    for(int i=1; i<=n; i++) p[i] = p[i-1]*B;

    for(int i=1; i<=n; i++)
        h1[i] = h1[i-1]*B + (s[i]=='0'?1:2);
    for(int i=n; i>=1; i--)
        h2[i] = h2[i+1]*B + (s[i]=='1'?1:2);

    long long ans = 0;
    for(int i=1; i<n; i++) {
        int l=0, r=min(i, n-i), res=0;
        while(l<=r) {
            int mid = l+r>>1;
            int L = i-mid+1, R = i+mid;
            if(L<1 || R>n) { r=mid-1; continue; }
            if(get1(L, i) == get2(i+1, R)) {
                res = mid;
                l = mid+1;
            } else r = mid-1;
        }
        ans += res;
    }
    cout << ans << '\n';
    return 0;
}