поразрядно

#include <iostream>
#include <cmath>
using namespace std;

long long cifra (long long a)
{
  long long znach = 0;
  long long a_1 = a;

  while(a_1 > 0)
  {
    znach++;
    a_1 /= 10;
  }

  znach--;
  return znach;
}

int main()
{
  long long a, b, result = 0;
  cin >> a >> b;

  long long a_1 = a;
  long long b_1 = b;

  long long znach, n1 = cifra(a), n2 = cifra(b);

  if (n1 > n2)
   result = a;
   else if (n2 > n1)
    result = b;
   else while (n1 >= 0)
  {
    znach = pow(10, n1);
    if (a/znach > b/znach)
     {
      result = a_1;
      goto printl;
     }
     if (a/znach < b/znach)
     {
       result =  b_1;
       goto printl;
     }
    a = a%znach;
    b = b%znach;
     n1 = n1-1;
  }

printl:
  if ( result == 0)
   cout << a_1;
   else cout << result;
}