题解：

#include<bits/stdc++.h>
using namespace std;
int main(){
    string a;
    int b[4];
    cin>>a;
    for(int i=0;i<4;i++){
    	b[i]=a[i]-'0';
    	b[i]=(b[i]+5)%10;
	}
	cout<<b[3]<<b[2]<<b[1]<<b[0];
    return 0;
}

#include using namespace std; int main(){ int n; cin>>n; int a =n/1000; int b =n/100%10; int c =n/10%10; int d =n%10; a+=5; b+=5; c+=5; d+=5; a%=10; b%=10; c%=10; d%=10; cout<<d<<c<<b<<a; return 0; }

#include using namespace std; int main(){ int n; cin>>n; int a =n/1000; int b =n/100%10; int c =n/10%10; int d =n%10; a+=5; b+=5; c+=5; d+=5; a%=10; b%=10; c%=10; d%=10; cout<<d<<c<<b<<a; return 0; }

#include<bits/stdc++.h> using namespace std; int main(){ int n;cin>>n; int a=n/1000; int b=n/100%10; int c=n/10%10; int d=n%10; a+=5; b+=5; c+=5; d+=5; a%=10; b%=10; c%=10; d%=10; cout<<d<<c<<b<<a; return 0; }