C++ control decimal place output

#include<iostream>
#include"math.h"
#include <iomanip> 
using namespace std;
int main(){
    int m;
    double n,sum=0;
   // int qiuhe(int i,int n);
    cin>>n>>m;
    //a=n;
   for(int i=0;i<m;i++){
    sum += n;
    n=sqrt(n);
}
    cout < < fixed << setprecision( 2 ) << sum;//Control the output of two decimal places
     return  0 ;
}