Buggy python submission (verdict: Runtime Error):
b = ["the", "this", "that"]
while 1:
        try:
                a = raw_input()
        except IndexError:
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                print a
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)

Fixed submission:
b = ["the", "this", "that"]
while 1:
        try:
                a = raw_input()
        except EOFError:
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)

Buggy python submission (verdict: Runtime Error):
b = ["the", "this", "that"]
while 1:
        try:
                a = raw_input()
        except IndexError:
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)

Fixed submission:
b = ["the", "this", "that"]
while 1:
        try:
                a = raw_input()
        except EOFError:
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)

Buggy python submission (verdict: Runtime Error):
b = ["the", "this", "that"]
while 1:
        a = raw_input()
        if a == "":
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)

Fixed submission:
b = ["the", "this", "that"]
while 1:
        try:
                a = raw_input()
        except EOFError:
                break
        for y in range(26):
                for x in b:
                        if x in a:
                                print a
                                break
                a = list(a)
                for x in range(len(a)):
                        if a[x] == "z":
                                a[x] = "a"
                        elif "a" <= a[x] < "z":
                                a[x] = chr(ord(a[x])+1)
                a = "".join(a)