Buggy python submission (verdict: Time Limit Exceeded):
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0] * ((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n%2==1:
        if SIEVES[(n-2)/2]!=0: x=1
    else:
        x=len([e for e in SIEVES if 0<e<=n/2 and SIEVES[(n-e)/2]!=0])
    return x
        
SIEVES=sieve(50000)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Fixed submission:
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0]*((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n<4:x=0
    elif n==4:x=1
    elif n%2==1:
        if S[n/2-1]: x=1
    else:
        a=n/2
        for e in PRIMES:
            if e>a: break
            if S[(n-e)/2]: x+=1
    return x

S=sieve(50000)
PRIMES=filter(None,S)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Buggy python submission (verdict: Runtime Error):
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0] * ((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n%2==1:
        if SIEVES[(n-2)/2]!=0: x=1
    else:
        for e in PRIMES:
            if e>n/2: break
            if SIEVES[(n-e)/2]!=0]:x+=1
    return x
        
SIEVES=sieve(50000)
PRIMES=filter(None,SIEVES)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Fixed submission:
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0]*((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n<4:x=0
    elif n==4:x=1
    elif n%2==1:
        if S[n/2-1]: x=1
    else:
        a=n/2
        for e in PRIMES:
            if e>a: break
            if S[(n-e)/2]: x+=1
    return x

S=sieve(50000)
PRIMES=filter(None,S)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0] * ((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    b=n/2
    if n==2 or n==3: return 1
    if n%2==1:
        if n-2 in PRIMES: x=1
    else:
        for e in PRIMES:
            if e>b:break
            if n-e in PRIMES: x+=1
    return x
        
SIEVES=sieve(50000)
PRIMES=filter(None,[2]+SIEVES)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Fixed submission:
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0]*((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n<4:x=0
    elif n==4:x=1
    elif n%2==1:
        if S[n/2-1]: x=1
    else:
        a=n/2
        for e in PRIMES:
            if e>a: break
            if S[(n-e)/2]: x+=1
    return x

S=sieve(50000)
PRIMES=filter(None,S)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Buggy python submission (verdict: Runtime Error):
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0]*((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n<4:x=0
    elif n==4:x=1
    elif n%2==1:
        if S[(n-2)/2]:
            x=1
    else:
        a=n/2
        for e in PRIMES:
            if e>a: break
            if S[(n-e)/2]:
                x+=1
    return x

S=sieve(50000)
PRIMES=filter(None,S)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)

Fixed submission:
import sys
def sieve(m):
    N=range(1,m+2,2)
    r=int(m**.5)
    h=len(N)
    N[0]=0
    for i in range(h):
        x=N[i]
        if x>r: break
        if x and i+x<h: N[i+x:h:x]=[0]*((h-1-i-x)/x+1)
    return N
def f0056(n):
    x=0
    if n<4:x=0
    elif n==4:x=1
    elif n%2==1:
        if S[n/2-1]: x=1
    else:
        a=n/2
        for e in PRIMES:
            if e>a: break
            if S[(n-e)/2]: x+=1
    return x

S=sieve(50000)
PRIMES=filter(None,S)
for n in sys.stdin:
    n=int(n)
    if n==0: break
    print f0056(n)