#include<iostream.h>
#include<string.h>

void main()
{
	char num[100];
	int i,sum,a;

	while(strcmp(num,"0")!=0){
		cin>>num;
		if (strcmp(num,"0")==0)
			break;
		if (strlen(num)==1){
			cout<<num<<endl;
			continue;
		}
		sum=0;
		for (i=0;i<int(strlen(num));i++)
			sum+=num[i]-'0';
		a=100;
		while(a>=10){
			a=0;
			while(sum!=0){
				a+=sum%10;
				sum=sum/10;
			}
			sum=a;
		}
		cout<<a<<endl;
	}
}

• runtime error (502) hawk 2004-03-13 16:08:49