#include <stdio.h>
#include <string.h>

long N;
long sol[20],i;


void ReadData(void){
  FILE *f = fopen("SUMA.IN","rt");
  fscanf(f,"%ld",&N);
  fclose(f);
}

void FindSolution(void){
long suma,ncif=0;
  suma=0;
  while (N){
    suma+=N % 10;
    N/=10;
    ncif++;
  }
  i=0;int carry=0;
  while (i!=ncif){
   carry=suma+carry;
   sol[i]=carry%10;
   carry=carry/10;
   i++;
  }
  if (carry!=0) sol[i]=carry;
   else i--;
}

void WriteSolution(void){
  FILE *f=fopen("SUMA.OUT","wt");
  while(i>=0)  fprintf(f,"%ld",sol[i--]);
  fclose(f);
}

void main(void){
  ReadData();
  FindSolution();
  WriteSolution();
}