C++ :

#include <bits/stdc++.h>
using namespace std;

int main(){
	int n;
	cin>>n;
	string s1,s2,s3 = "";
	s1 = "4567";
	s2 = "123";
	while(s3.size() < n){
		s3 = s2 + s1;
		s1 = s2;
		s2 = s3;
	}
	
	cout<<s3[n - 1]<<endl;
}

Pascal :

program chaojizifuchuan;
var
  n,tochange,tcd:longint;

function need(t1:longint):longint;
var
  sum,xh,sum2,su:longint;
begin
  xh:=2;             
  sum:=7;           
  sum2:=10;          
  while sum2<t1 do       
  begin
    inc(xh);                
    su:=sum2;               
    sum2:=sum+sum2;        
    sum:=su;                
  end;
  if t1<=7 then xh:=1;   
  tochange:=sum2;    
  tcd:=sum;             
  exit(xh);            
end;

procedure printf(t2:char);
begin
  writeln(t2);       
  halt;              
end;

procedure try(len:longint);
var
  bu,total,last:longint;
  c:string;
begin
  if len<=7 then begin              
                         c:='1234567';
                         printf(c[len]);
                     end
  else begin                             
            bu:=need(len);                
            total:=tochange;               
            tochange:=0;                    
            if odd(bu) then last:=4
                  else last:=3; 
            if len>=total-last then begin 
                                                if last=4 then c:='4567'
                                                   else c:='123'; 
                                                printf(c[len-total+last]); 
                                            end
            else begin
                     dec(bu);
                     total:=tcd; 
                     tcd:=0; 
                     try(len-total);
                   end;
        end;

end;
begin
    readln(n);            
    try(n);                   
end.