include

include

char a[10005];
long long sum;
using namespace std;
int main()
{
freopen("number.in","r",stdin);
freopen("number.out","w",stdout);
for(int i=0;i<8;i++)
cin>>a[i];
for(int i=0;i<8;i++)
if(a[i]=='1')
sum++;
{
cout<<sum<<endl;
return 0;
}

}