C++ :

#include <iostream>
#include <fstream>

using namespace std;

int n;
ifstream fin("p1.in");
ofstream fout("p1.out");
double k, s = 0.0;
//#define cin fin
//#define cout fout

main()
{
	cin >> k;
	fin.close();
	
	for (n = 1; s <= k; ++n)
		s += 1.0 / (double)n;
		
	cout << --n;
	fout.close();
//	for(;;);
}

Pascal :

var  k,i:longint;t:real;
begin
    readln(k);
    t:=1;
    i:=1;
    while t<=k do
     begin
         i:=i+1;
         t:=t+1/i;
     end;
    writeln(i);
end.