#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 d; cin>>d; int a=d%10; int b=(d/10)%10; int c=d/100; cout<<a+b+c<<endl; return 0; }