#include<bits/stdc++.h>
using namespace std;
int main(){
string s;
cin>>s;
for(unsigned long long int i=0;i<s.size();i++){
char c=s.at(i);
int num= c-‘0’;
int nenum = 9-num;
if(nenum<num){
s[i]=(char)(nenum + 48);
}
}
cout<<s<<endl;
return 0;
}
@chetan_aggarwalbX1
999 ans 900 , your ans 000 check it ( you dont have to change first character if its 9)
hope its clear if yes dont forget to hit like and mark resolved 
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