Codeforces 556A - Case of the Zeros and Ones

 #include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
#include <string>
#include <vector>
#include <cmath>
#include <cctype>
#include <sstream>
#include <set>
#include <list>
#include <stack>
#include <queue>
#include <algorithm>
#define sf scanf
#define pf printf
#define sfint scanf ("%d %d",&a,&b)
#define sfl scanf ("%ld %ld",&a,&b)
#define sfll scanf ("%lld %lld",&a,&b)
#define sfd scanf ("%lf %lf",&a,&b)
#define sff scanf ("%f %f",&a,&b)
#define lp1(i,n) for(i=0;i<n;i++)
#define lp2(i,n) for(i=1;i<=n;i++)
#define LL long long
#define L long
#define mem(c,v) memset(c,v,sizeof(c))
#define ui unsigned int
#define ull unsigned long long int
#define nl puts("")
#define sq(x) ((x)*(x))
#define MX 2000005
#define N 100
#define MOD 10000000007
#define pb push_back
#define pi acos(-1.0)
#define sz size()
#define gc getchar ()
#define ps push
#define clr clear
#define inf 2147483647
#define bn begin()
#define ed end()

using namespace std;

char ch[MX];

int main()
{
    ull n,i,j,cnt=0,zero=0,one=0;

    sf("%llu\n",&n);

    lp1(i,n)
    {
        sf("%c",&ch[i]);
    }

    //lp1(i,strlen(ch)) pf("%c",ch[i]);
    ull len=strlen(ch);

    lp1(i,len)
    {
        if(ch[i]=='1')
        {
            one++;
        }

        else
        {
            zero++;
        }
    }

    if(one > zero)
    {
        pf("%llu",one-zero);
    }

    else
    {
        pf("%llu",zero-one);
    }

    return 0;
}