#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a,b,c,d; cin>>a; b=a%10,c=(a%100-b)/10,d=(a%1000-b-c)/100; cout<<b+c+d; return 0; }