Div 3 A. Wrong subtraction

// https://codeforces.com/contest/977/problem/A
#include <iostream>
#include <string>
using namespace std;
int main()
{
  int n = 0, k =0;
  cin >> n >> k;
  while(k--)
  {
      if(n%10==0)
      {
          n /=10;
      }
      else
      {
          n--;
      }
  }
  cout << n;
}