解答

如下

#include <bits/stdc++.h>
using namespace std;
int main(){
    double s,m=0,k=0,l=0;
    cin>>s;
    l=2;
    while(m<s){
        m=m+l;
        l=l*0.98;
        k++;
    }
    cout<<k;
    return 0;
}