Buggy python submission (verdict: Runtime Error):
N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
def nap(N,goods):
    dp=[-1*float('inf')]*(N+1)
    dp[0]=0
    for i in range(N):
        for w,v in goods:
            if i+w<=N:
                dp[i+w]=max(dp[i+w],dp[i]+v)
    return max([dp[i]+N-i for i in range(N+1)])
goods1=[(a,b) for a,b in zip(A,B) if a<b]
goods2=[(b,a) for a,b in zip(A,B) if a>b]
N=nap(N,[(a,b) for a,b in zip(A,B)])
if len(goods2)==0:
    print(N)
elif len(goods2)==1:
    print(N%goods2[0]+(N//goods2[0])*goods2[1])
elif len(goods2)==3:
    print(nap(N,goods2))
else:
    a,b,c,d=goods2[0][0],goods2[0][1],goods2[1][0],goods2[1][1]
    if b-a<d-c:
        a,b=c,d
    elif b-a==d-c and a>c:
        a,b=c,d
    bord=(N//a)*b+((N%a)//c)*d
    x=N//a
    ans=bord
    for i in range(1,1+x):
        now=(x-i)*b+((N-(x-i)*a)//c)*d
        if now+d<bord:
            break
        else:
            ans=max(ans,now)
    print(ans)

Fixed submission:
N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
def nap(N,goods):
    dp=[-1*float('inf')]*(N+1)
    dp[0]=0
    for i in range(N):
        for w,v in goods:
            if i+w<=N:
                dp[i+w]=max(dp[i+w],dp[i]+v)
    return max([dp[i]+N-i for i in range(N+1)])
goods1=[(a,b) for a,b in zip(A,B) if a<b]
goods2=[(b,a) for a,b in zip(A,B) if a>b]
if len(goods1)>0:
    N=nap(N,[(a,b) for a,b in zip(A,B)])
if len(goods2)==0:
    print(N)
elif len(goods2)==1:
    print(N%goods2[0][0]+(N//goods2[0][0])*goods2[0][1])
elif len(goods2)==3:
    print(nap(N,goods2))
else:
    a,b,c,d=goods2[0][0],goods2[0][1],goods2[1][0],goods2[1][1]
    if (b-a)/a<(d-c)/c:
        a,b,c,d=c,d,a,b
    elif (b-a)/a==(d-c)/c and a>c:
        a,b,c,d=c,d,a,b
    bord=(N//a)*b+((N%a)//c)*d+(N%a)%c
    x=N//a
    ans=bord
    for i in range(1,1+x):
        now=(x-i)*b+((N-(x-i)*a)//c)*d+(N-(x-i)*a)%c
        if now+d<ans:
            break
        else:
            ans=max(ans,now)
    print(ans)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
def nap(N,goods):
    dp=[-1*float('inf')]*(N+1)
    dp[0]=0
    for i in range(N):
        for w,v in goods:
            if i+w<=N:
                dp[i+w]=max(dp[i+w],dp[i]+v)
    return max([dp[i]+N-i for i in range(N+1)])
goods1=[(a,b) for a,b in zip(A,B) if a<b]
goods2=[(b,a) for a,b in zip(A,B) if a>b]
N=nap(N,[(a,b) for a,b in zip(A,B)])
if len(goods2)==0:
    print(N)
elif len(goods2)==1:
    print(N%goods2[0]+(N//goods2[0])*goods2[1])
elif len(goods2)==3:
    print(nap(N,goods2))
else:
    a,b,c,d=goods2[0][0],goods[0][1],goods[1][0],goods[1][1]
    if b-a<d-c:
        a,b=c,d
    elif b-a==d-c and a>c:
        a,b=c,d
    bord=(N//a)*b+((N%a)//c)*d
    x=N//a
    ans=bord
    for i in range(1,1+x):
        now=(x-i)*b+((N-(x-i)*a)//c)*d
        if now+d<bord:
            break
        else:
            ans=max(ans,now)
    print(ans)

Fixed submission:
N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
def nap(N,goods):
    dp=[-1*float('inf')]*(N+1)
    dp[0]=0
    for i in range(N):
        for w,v in goods:
            if i+w<=N:
                dp[i+w]=max(dp[i+w],dp[i]+v)
    return max([dp[i]+N-i for i in range(N+1)])
goods1=[(a,b) for a,b in zip(A,B) if a<b]
goods2=[(b,a) for a,b in zip(A,B) if a>b]
if len(goods1)>0:
    N=nap(N,[(a,b) for a,b in zip(A,B)])
if len(goods2)==0:
    print(N)
elif len(goods2)==1:
    print(N%goods2[0][0]+(N//goods2[0][0])*goods2[0][1])
elif len(goods2)==3:
    print(nap(N,goods2))
else:
    a,b,c,d=goods2[0][0],goods2[0][1],goods2[1][0],goods2[1][1]
    if (b-a)/a<(d-c)/c:
        a,b,c,d=c,d,a,b
    elif (b-a)/a==(d-c)/c and a>c:
        a,b,c,d=c,d,a,b
    bord=(N//a)*b+((N%a)//c)*d+(N%a)%c
    x=N//a
    ans=bord
    for i in range(1,1+x):
        now=(x-i)*b+((N-(x-i)*a)//c)*d+(N-(x-i)*a)%c
        if now+d<ans:
            break
        else:
            ans=max(ans,now)
    print(ans)