Решение задачи File 18

import random

def GenerateLine(fname):
    N = random.randrange(1,10)
    print("N = ",N)
    #N = 2
    #line = "1, 5, 5, 5, 4, 4, 5"
    try:
        f = open(fname, "w")
        try:
            for i in range(N):
                line = str(random.randint(1,4))+"\n"
                f.write(line)
        finally:
            f.close()
    except IOError:
        print('Write error: ',fname)

f_input = "file18_input.txt"
#GenerateLine(f_input)

i = 0
flag = False
try:
    with open(f_input,'r') as f_in:
        for line in f_in:
            i += 1
            x = int(line.strip())
            print(x)    
            if i == 1:
                x1 = x
            elif i == 2:
                x2 = x
                if x1 < x2:
                    l_min = x1
                    flag = True
                    break
            elif i == 3:
                x3 = x
                if x1 >= x2 and x2 < x3:
                    l_min = x2
                    flag = True
                    break
            else:
                x1 = x2
                x2 = x3
                x3 = x
                if x1 >= x2 and x2 < x3:
                    l_min = x2
                    flag = True
                    break

except IOError:
    print('Open error: ',f_source)
        
if not flag:
    if i == 1:
        l_min = x1
    else:
        l_min = x        
            
print("First local minimum:",l_min)
									

program File18;
var
 S:String;
 F_in,F_out: File of Real;
 El2,El1,El:Real;
begin
  Write('File: ');
  Readln(S);
  Assign(F_in,S);
  Reset(F_in);
  Read(F_in,El1);
  Read(F_in,El);
  El2:=El1;
  if (El1<El) then Writeln(El1)
  else
   begin
    while (not eof(F_in)) and not((El>El1) and (El1<El2)) do
     begin
      El2:=El1;
      El1:=El;
      Read(F_in,El);
     end;
    if (not eof(F_in)) then Writeln(El1)
    else if eof(F_in) and (El1>El) then  Writeln(El);
   end;
  Close(F_in);
end.