题解

代码如下

#include "iostream"
using namespace std;
int main(int argc, char **argv){
    int a;
    cin>>a;
    int c = 0,b = 1;
    while(a!=0){
        if(a%10==4){
            c+=8*b;
        }else{
            c+=(a%10)*b;
        }
        a/=10;
        b*=10;
    }
    cout<<c;
    return 0;
}