Buggy python submission (verdict: Runtime Error):
import cmath
import math
import itertools
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(m)


Fixed submission:
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
ma=0
#math.piに注意
for i in range(n):
    z=a[i]
    c=b[i]-math.pi/2
    d=b[i]+math.pi/2
    l=max([c,-math.pi])
    r=min([d,math.pi])
    #(0,0)の時は偏角が0になってしまうし、除く
    #あとは-piとpiどっちになるか→piになる
    if a[i]!=complex(0,0):
        for j in range(n):
            if j!=i:
                #境界条件の場合分けがむずい
                if l<=b[j]<=r or (c<=-math.pi and c+2*math.pi<=b[j]<=math.pi) or (d>=math.pi and -math.pi<=b[j]<=d-2*math.pi):
                    z+=a[j]
    ma=max([abs(z),ma])
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1 and a[i]+a[i+1]!=0:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(max([m,ma]))

Buggy python submission (verdict: Runtime Error):
import cmath
import math
import itertools
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        zc,zd=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1:
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(m)


Fixed submission:
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
ma=0
#math.piに注意
for i in range(n):
    z=a[i]
    c=b[i]-math.pi/2
    d=b[i]+math.pi/2
    l=max([c,-math.pi])
    r=min([d,math.pi])
    #(0,0)の時は偏角が0になってしまうし、除く
    #あとは-piとpiどっちになるか→piになる
    if a[i]!=complex(0,0):
        for j in range(n):
            if j!=i:
                #境界条件の場合分けがむずい
                if l<=b[j]<=r or (c<=-math.pi and c+2*math.pi<=b[j]<=math.pi) or (d>=math.pi and -math.pi<=b[j]<=d-2*math.pi):
                    z+=a[j]
    ma=max([abs(z),ma])
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1 and a[i]+a[i+1]!=0:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(max([m,ma]))

Buggy python submission (verdict: Runtime Error):
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
m=0
#math.piに注意
for i in range(n):
    za,zb=complex(0,0),complex(0,0)
    if a[i]!=complex(0,0):
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<p<=0:
                za+=a[j]
            if 0<=p<math.pi:
                zb+=a[j]
    '''
    print(za)
    print(zb)
    print(abs(za))
    print(abs(zb)):
    '''
    m=max([m,za,zb,abs(max([za-a[i],0])),abs(max([zb-a[i],0]))])
print(m)


Fixed submission:
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
ma=0
#math.piに注意
for i in range(n):
    z=a[i]
    c=b[i]-math.pi/2
    d=b[i]+math.pi/2
    l=max([c,-math.pi])
    r=min([d,math.pi])
    #(0,0)の時は偏角が0になってしまうし、除く
    #あとは-piとpiどっちになるか→piになる
    if a[i]!=complex(0,0):
        for j in range(n):
            if j!=i:
                #境界条件の場合分けがむずい
                if l<=b[j]<=r or (c<=-math.pi and c+2*math.pi<=b[j]<=math.pi) or (d>=math.pi and -math.pi<=b[j]<=d-2*math.pi):
                    z+=a[j]
    ma=max([abs(z),ma])
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1 and a[i]+a[i+1]!=0:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(max([m,ma]))

Buggy python submission (verdict: Runtime Error):
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    if (x,y)!=(0,0):
        a.append(complex(x,y))
        b.append(cmath.phase(a[i]))
    else:
        n-=1
#a.sort(key=cmath.phase)
m=0
#math.piに注意
for i in range(n):
    za,zb=0,0
    for j in range(n):
        p=cmath.phase(a[j]/a[i])
        if -math.pi<=p<=0:
            za+=a[j]
        if 0<=p<=math.pi:
            zb+=a[j]
    m=max([abs(za),abs(zb),abs(za-a[i]),abs(zb-a[i]),m])
print(m)


Fixed submission:
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
ma=0
#math.piに注意
for i in range(n):
    z=a[i]
    c=b[i]-math.pi/2
    d=b[i]+math.pi/2
    l=max([c,-math.pi])
    r=min([d,math.pi])
    #(0,0)の時は偏角が0になってしまうし、除く
    #あとは-piとpiどっちになるか→piになる
    if a[i]!=complex(0,0):
        for j in range(n):
            if j!=i:
                #境界条件の場合分けがむずい
                if l<=b[j]<=r or (c<=-math.pi and c+2*math.pi<=b[j]<=math.pi) or (d>=math.pi and -math.pi<=b[j]<=d-2*math.pi):
                    z+=a[j]
    ma=max([abs(z),ma])
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1 and a[i]+a[i+1]!=0:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(max([m,ma]))

Buggy python submission (verdict: Runtime Error):
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
m=0
#math.piに注意
for i in range(n):
    za,zb=0,0
    if a[i]!=complex(0,0):
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
    m=max([abs(za),abs(zb),abs(za-a[i]),abs(zb-a[j]),m])
print(m)


Fixed submission:
import cmath
import math
n=int(input())
a=[]
b=[]
#偏角ソートの方が楽
for i in range(n):
    x,y=map(int,input().split())
    a.append(complex(x,y))
    b.append(cmath.phase(a[i]))
#a.sort(key=cmath.phase)
ma=0
#math.piに注意
for i in range(n):
    z=a[i]
    c=b[i]-math.pi/2
    d=b[i]+math.pi/2
    l=max([c,-math.pi])
    r=min([d,math.pi])
    #(0,0)の時は偏角が0になってしまうし、除く
    #あとは-piとpiどっちになるか→piになる
    if a[i]!=complex(0,0):
        for j in range(n):
            if j!=i:
                #境界条件の場合分けがむずい
                if l<=b[j]<=r or (c<=-math.pi and c+2*math.pi<=b[j]<=math.pi) or (d>=math.pi and -math.pi<=b[j]<=d-2*math.pi):
                    z+=a[j]
    ma=max([abs(z),ma])
m=0
#math.piに注意
for i in range(n):
    if a[i]!=complex(0,0):
        za,zb=complex(0,0),complex(0,0)
        for j in range(n):
            p=cmath.phase(a[j]/a[i])
            if -math.pi<=p<=0:
                za+=a[j]
            if 0<=p<=math.pi:
                zb+=a[j]
        m=max([m,abs(za),abs(zb)])
        if i!=n-1 and a[i]+a[i+1]!=0:
            zc,zd=complex(0,0),complex(0,0)
            for j in range(n):
                p=cmath.phase(a[j]/((a[i]+a[i+1])/2))
                if -math.pi<=p<=0:
                    zc+=a[j]
                if 0<=p<=math.pi:
                    zd+=a[j]
            m=max([m,abs(zc),abs(zd)])

print(max([m,ma]))