Huge_Control

#include <fstream>
using namespace std;
ifstream f("hugecontrol.in");
ofstream g("hugecontrol.out");
char c;
unsigned long long s,cs,sn; /// s=suma cifrelor;cs=copia lui s,sn=s nou
int main()
{
    while(f>>c)
        s+=c-'0';
    while(s>9)
    {
        cs=s;
        sn=0;
        while(cs!=0)
            sn+=cs%10,cs/=10;
        s=sn;
    }
    g<<s;
    return 0;
}