include
using namespace std;
int main() {
char c[8];
bool d[8];
int a = 0;
for (int i = 0; i <= 7; i++) {
cin >> c[i];
if (c[i] == '1') {
d[i] = true;
} else {
d[i] = false;
}
}
for (int i = 0; i <= 7; i++) {
if (d[i] == true) {
a++;
}
}
printf("%d", a);
return 0;
}