问题不大

#include<iostream>
using namespace std;
int main(){
string a;
string c="10X98765432";
cin>>a;
if(a.length()!=18){
cout<<"No";
return 0;
}
int num=0;
int b[17]={7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2};
for(int i=0;i<17;i++){
if(!isdigit(a[i])){
cout<<"No";
return 0;
}
num+=(a[i]-'0')*b[i];
}
num%=11;
if(a[17]==c[num]){
cout<<"Yes" ;
}else{
cout<<"No";
}
}