//求数根
#include<stdio.h> int fun(int a); int main() { int a; char c; while(1) { scanf("%c",&c); if(c=='0') break; a=c-'0'; while(scanf("%c",&c)!=EOF) { if(c=='\n') break; a=fun(a+c-'0'); } printf("%d\n",a); } return 0; } int fun(int a) { int s=0; while(a>0) { s+=a%10; a/=10; } return s; }