#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,remainder,cnt=0,i,temp1;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        temp1=i;
        while(temp1)
        {
           remainder=temp1%10;
           if(remainder==0)
           {
                cnt++;
                break;
           }
           temp1=temp1/10;
        }
    }
    printf("%d",cnt);
}

Input:

110

Output:

20

Explanation:

For loop runs till entered number i.e n. Within for loop value of variable i is assigned to temp1 and while loop inside for loop runs till temp1 is true. A remainder is obtained by using modulus operator i.e temp1 % 10. A number if contain digit 0 when divided by 10 will give remainder 0 thus if condition is used to check value of remainder if 0 value of counter i.e cnt is incremented and finally dividing temp1 with 10. This procedure can be used to count number of integers from 1 to N contains 0's as a digit