#include<stdio.h>

int main()

{

int n , sum = 0 ;

scanf("%d",&n);

char a[n];

scanf("%s",a);

int i = 0;

while( i<n )

{

if(a[i]=='0')

{

sum++;

}

i++;

}

printf("%d",sum);

return 0;

}

#include <cstdio> #include <cstdlib> using namespace std; int main() { int t; scanf("%d",&t); while (t--) { int n; scanf("%d",&n); long long sum=(1+n)1lln/2; //for (int i=1;i<=n;i++) // sum=sum+i; printf("%lld\n",sum); } return 0; }

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e6+10;

signed main()
{
	int t=1;
	//cin>>t;
	while(t--)
	{
		int n;
		cin>>n;
	 string s;
	 cin>>s;
	 int ans=0;
	 for(int i=0;i<s.length();i++)ans=ans+(s[i]=='0');
	 cout<<ans<<'\n';
	}
}