#include <bits/stdc++.h>
int main() {
	int n;
	std::cin>>n;
	long long f=0;
	for(int e=1;e<=n;e++){
		long long b=0,c=1,d=0;
		b=e;
		while(b){
			c=c*10;
			d=d*10+b%10;
			b=b/10;
		}
		f+=e*c+d;
	}
	
	//题解在此
	std::cout<<f;
}

快看吧！ #include<bits/stdc++.h> using namespace std; int main(){ int n; cin>>n; long long ans=0; for(int i=1;i<=n;i++){ long long len1=0,len2=1,len3=0; len1=i; while(len1){ len2=len210; len3=len310+len1%10; len1=len1/10; } ans=ans+i*len2+len3; } cout<<ans; return 0; } ！！！！！！！！！！！！！！！

vyc

zgs

#include<bits/stdc++.h> using namespace std; int main(){ int n; cin>>n; long long ans=0; for(int i=1;i<=n;i++){ long long len1=0,len2=1,len3=0; len1=i; while(len1){ len2=len210; len3=len310+len1%10; len1=len1/10; } ans=ans+i*len2+len3; } cout<<ans; return 0; }