https://www.bilibili.com/video/BV18g41157hc?t=61.2

#include<bits/stdc++.h> using namespace std; int main(){ int x,n,z,y,m; cin>>n>>x; for(int i=1;i<=n;i++){ y=i; while(y!=0){ m=y%10; if(m==x){ z=z+1; } y=y/10;

}

}cout<<z; }