FindZeroHash - My python beginning program, my first python program!

findHash.py

#!/usr/bin/python

import sha;
import sys;
import time;
def checkifzero(str, count):
    sa = sha.new(str).digest();
    return sa.startswith('\x00' * count);

if len(sys.argv) != 5:
    sys.stderr.write ("""\
Command: ./findHash.py <start-text-file> <from> <to> <zero count>

Wrote by wtm""");
    exit(1);

stfName = sys.argv[1];
stfF = open(stfName, 'r');
stfCt = stfF.read();

zeroc = int(sys.argv[4]);

sys.stderr.write("Finding \"" + stfCt + ("_" * zeroc) + "\" . sha1 startswith " + ("0" * zeroc) + "\n");

start = int(sys.argv[2]);
end = int(sys.argv[3]);

sys.stderr.write("From " + str(start) + " to " + str(end) + "\n");

now = start;
lastPgr = time.time();
while now < end:
    ifc = checkifzero(stfCt + str(now), zeroc);
    if ifc:
        sys.stderr.write("Find "+stfCt);
        sys.stderr.flush();
        sys.stdout.write(str(now));
        sys.stdout.flush();
        sys.stderr.write(" gots a sha1 starts with ");
        sys.stderr.write("0" * zeroc);
        sys.stderr.write(" ");
        sys.stdout.write("\n");
        sys.stderr.flush();
    elif time.time() - lastPgr > 20:
        sys.stderr.write("    Finding to " + str(now) + "\n");
        lastPgr = time.time();
    now+=1;
sys.stderr.write("Done.\n");