C++ :

#include<iostream>
using namespace std;
int main()
{
	int m,n=1;
	double sum=0;
	cin>>m;
	do
	{
		sum+=1.0/n;
		n++;
	} while (sum<=m);
	cout<<n-1<<endl;
	return 0;
}

Pascal :

var  s:real;
     n,m:integer;
begin
  s:=0;
  n:=0;
  readln(m);
  while s<=m do
  begin
    n:=n+1;
    s:=s+1/n;
  end;
  writeln(n);
end.