Inmultire nr mari

#include <fstream>

using namespace std;
ifstream fin("date.in");
ofstream fout("date.out");
int a[1000];
int main()
{
    char c;
    while(fin>>c)
    {
        if(c>='0' && c<='9')
        {
            a[0]++;
            a[a[0]]=c-48;
        }
        else break;
    }
    int k;
    fin>>k;
    int transport=0;
    for(int i=a[0];i>=1;i--)
    {
        if(transport==0)
        {
            transport=(a[i]*k-(a[i]*k)%10)/10;
            a[i]=(a[i]*k)%10;
        }
        else
        {
            a[i]=(a[i]*k)%10+transport;
            transport=(a[i]-a[i]%10)/10;
        }
    }
    for(int i=1;i<=a[0];i++)
        fout<<a[i];
    fin.close();
    fout.close();
    return 0;
}