Problem description
Little girl Tanya is learning how to decrease a number by one, but she does it wrong with a number consisting of two or more digits. Tanya subtracts one from a number by the following algorithm:
- if the last digit of the number is non-zero, she decreases the number by one;
- if the last digit of the number is zero, she divides the number by 10 (i.e. removes the last digit).
You are given an integer number n. Tanya will subtract one from it k times. Your task is to print the result after all k subtractions.
It is guaranteed that the result will be positive integer number.
Input
The first line of the input contains two integer numbers n and k (2≤n≤10^9, 1≤k≤50) — the number from which Tanya will subtract and the number of subtractions correspondingly.
Output
Print one integer number — the result of the decreasing n by one k times.
It is guaranteed that the result will be positive integer number.
Examples
Input
512 4
Output
50
Input
1000000000 9
Output
1
Note
The first example corresponds to the following sequence: 512→511→510→51→50512→511→510→51→50.
解题思路：题目的意思就是给一个数n和要求执行k次操作：如果尾数是0，那么n/=10；否则就n-=1；简单模拟即可！
AC代码：
1 #include <bits/stdc++.h> 2 using namespace std; 3 int main() 4 { 5 int n,k; 6 cin>>n>>k; 7 for(int i=1;i<=k;++i){ 8 if(n%10)n-=1; 9 else n/=10; 10 } 11 cout<<n<<endl; 12 return 0; 13 }