#include <bits/stdc++.h>
using namespace std;
string st;
int d,i,dem;
int main()
{
cin>>st;
d=st.length();
dem=0;
for (i=0; i<d; i++)
if (st[i]=='0') dem++;
cout<<dem;
return 0;
}
Var n,dem:longint;
Begin
Write('Nhap so n = ');readln(n);
While n >= 10 do
Begin
if n mod 10 = 0 then dem:=dem+1;
n:=n div 10;
End;
Write('So vua nhap co ',dem,' so 0');
Readln;
End.