#include <iostream>
using namespace std;
int main()
{
int a,b,k;
cin>>a>>b>>k;
int cnt=0;
for(int x=a;x<=b;x++)
{
int xx=x;
while(xx>0)
{
if(xx%10==k)
cnt++;
xx=xx/10;
}
}
cout<<cnt<<endl;
return 0;
}

#include <iostream>
using namespace std;
int main()
{
    int a,b,k;
    cin>>a>>b>>k;
    int cnt=0;
    for(int x=a;x<=b;x++)
    {
        int xx=x;
        while(xx>0)
        {
            if(xx%10==k)
                cnt++;
            xx=xx/10;
        }
    }
    cout<<cnt<<endl;
    return 0;
}