https://www.luogu.com.cn/problem/U490532

#include<bits/stdc++.h>
using namespace std;
int main(){
    double a;
    cin>>a;
    double a3=a;
    double x=0;
    while(!(1<=a3&&a3<10)){
        a3/=10;
        x+=a3/10;
    }
    cout<<a3<<"*10^"<<x;
    return 0;
}