C

    #define _CRT_SECURE_NO_WARNINGS

    #include <iostream>
    #include <algorithm>
    #include <cmath>
    #include <string>
    #include <vector>
    #include <map>
    #include <set>
    #include <queue>
    #include <assert.h>

    using namespace std;

    #define ll long long
    #define ull unsigned long long
    const ll INF = 1e18;
    const double PI = acos(-1.0);



    int main()
    {
        //freopen("INPUT.TXT", "r", stdin);
        //freopen("OUTPUT.TXT", "w", stdout);
        ios::sync_with_stdio(false);

        int n;
        cin >> n;
        string s;
        cin >> s;

        int cnt0 = 0, cnt1 = 0;
        for (int i = 0; i < n; i++)
        {
            if (s[i] == '0')
                cnt0++;
            else
                cnt1++;
        }

        int mini = min(cnt0, cnt1);
        int res = n - mini * 2;
        cout << res;

        //system("pause");
        return 0;
    }