Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin

def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,stdin.readline().split())))
        c.append(tobit(list(map(int,stdin.readline().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp0 = [-1 for i in range(2**n)]
    dp1 = [-1 for i in range(2**n)]
    dp0[0] = 0
    dp1[0] = 0
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp0 = [-1 for i in range(2**n)]
        temp1 = [-1 for i in range(2**n)]
        for j in range(2**n):
            if dp0[j]==-1 and dp1[j]==-1:
                continue
            new = dp0[j]
            new2 = dp1[j]
            if new==-1 or new2<new:
                if new2!=-1:
                    new = new2
            temp1[j] = new
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            target = temp0[update]
            if target==-1:
                temp0[update] = new+curc
            elif target>new+curc:
                temp0[update] = new+curc                
            
        dp0 = temp0
        dp1 = temp1
        #print(dp)
    ans = dp1[2**n-1]
    if ans==-1:
        print(dp0[2**n-1])
    else:
        if ans>dp1[2**n-1] and dp1[2**n-1]!=-1:
            print(dp1[2**n-1])
        else:
            print(ans)  
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)

Fixed submission:
from sys import stdin

def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,stdin.readline().split())))
        c.append(tobit(list(map(int,stdin.readline().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp = [-1 for i in range(2**n)]
    dp[0] = 0
    
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp = [-1 for i in range(2**n)]
        for j in range(2**n):
            if dp[j]==-1:
                continue
            new = dp[j]
            
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            target = temp[update]
            if target==-1:
                temp[update] = new+curc
            elif target>new+curc:
                temp[update] = new+curc                
            if new<temp[j] or temp[j]==-1:
                temp[j] = dp[j]
        dp = temp
        #print(dp)
    print(dp[-1])
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)

Buggy python submission (verdict: Time Limit Exceeded):
from sys import stdin

def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,stdin.readline().split())))
        c.append(tobit(list(map(int,stdin.readline().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp = [[-1,-1] for i in range(2**n)]
    dp[0] = [0,0]
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp = [[-1,-1] for i in range(2**n)]
        for j in range(2**n):
            if dp[j]==[-1,-1]:
                continue
            new = dp[j][0]
            new2 = dp[j][1]
            if new==-1 or new2<new:
                if new2!=-1:
                    new = new2
            temp[j][1] = new
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            target = temp[update][0]
            if target==-1:
                temp[update][0] = new+curc
            elif target>new+curc:
                temp[update][0] = new+curc                
            
        dp = temp
        #print(dp)
    ans = dp[2**n-1]
    ans.sort()
    if dp[0]==-1:
        print(ans[1])
    else:
        print(ans[0])   
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)

Fixed submission:
from sys import stdin

def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,stdin.readline().split())))
        c.append(tobit(list(map(int,stdin.readline().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp = [-1 for i in range(2**n)]
    dp[0] = 0
    
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp = [-1 for i in range(2**n)]
        for j in range(2**n):
            if dp[j]==-1:
                continue
            new = dp[j]
            
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            target = temp[update]
            if target==-1:
                temp[update] = new+curc
            elif target>new+curc:
                temp[update] = new+curc                
            if new<temp[j] or temp[j]==-1:
                temp[j] = dp[j]
        dp = temp
        #print(dp)
    print(dp[-1])
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)

Buggy python submission (verdict: Time Limit Exceeded):
def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,input().split())))
        c.append(tobit(list(map(int,input().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp = [[-1,-1] for i in range(2**n)]
    dp[0] = [0,0]
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp = [[-1,-1] for i in range(2**n)]
        for j in range(2**n):
            if dp[j]==[-1,-1]:
                continue
            new = dp[j][0]
            if new==-1 or dp[j][1]<new:
                if dp[j][1]!=-1:
                    new = dp[j][1]
            temp[j][1] = new
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            if temp[update][0]==-1:
                temp[update][0] = new+curc
            elif temp[update][0]>new+curc:
                temp[update][0] = new+curc                
            
        dp = temp
        #print(dp)
    ans = dp[2**n-1]
    ans.sort()
    if dp[0]==-1:
        print(ans[1])
    else:
        print(ans[0])   
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)

Fixed submission:
from sys import stdin

def getval():
    n,m = map(int,input().split())
    ab = []
    c = []
    def tobit(arr):
        idx = len(arr)-1
        s = ""
        for i in range(n-1,-1,-1):
            if arr[idx]-1==i and idx!=-1:
                s = "".join([s,"1"])
                idx -= 1
            else:
                s = "".join([s,"0"])
        return s
    for i in range(m):
        ab.append(list(map(int,stdin.readline().split())))
        c.append(tobit(list(map(int,stdin.readline().split()))))
    return n,m,ab,c 

def main(n,m,ab,c):
    dp = [-1 for i in range(2**n)]
    dp[0] = 0
    
    
    def intersect(bit1,bit2):
        s = ""
        for i in range(n):
            if bit1[i]=="1" or bit2[i]=="1":
                s = "".join([s,"1"])
            else:
                s = "".join([s,"0"])
        return int(s,2)

    for i in range(m):
        curc = ab[i][0]
        curk = c[i]
        temp = [-1 for i in range(2**n)]
        for j in range(2**n):
            if dp[j]==-1:
                continue
            new = dp[j]
            
            s = bin(j)[2:]
            if len(s)!=n:
                while len(s)<n:
                    s = "".join(["0",s])
            update = intersect(curk,s)
            
            #print(i,j,update,new,curc,curk,s)
            target = temp[update]
            if target==-1:
                temp[update] = new+curc
            elif target>new+curc:
                temp[update] = new+curc                
            if new<temp[j] or temp[j]==-1:
                temp[j] = dp[j]
        dp = temp
        #print(dp)
    print(dp[-1])
        
                
if __name__=="__main__":
    n,m,ab,c = getval()
    main(n,m,ab,c)