Buggy python submission (verdict: Runtime Error):
import sys
s2nn = lambda s: [int(c) for c in s.split(' ')]
ss2nn = lambda ss: [int(s) for s in ss]
ss2nnn = lambda ss: [s2nn(s) for s in ss]
i2s = lambda: sys.stdin.readline().rstrip()
i2n = lambda: int(i2s())
i2nn = lambda: s2nn(i2s())
ii2ss = lambda n: [sys.stdin.readline().rstrip() for _ in range(n)]
ii2sss = lambda n: [list(sys.stdin.readline().rstrip()) for _ in range(n)]
ii2nn = lambda n: ss2nn(ii2ss(n))
ii2nnn = lambda n: ss2nnn(ii2ss(n))

from collections import defaultdict  # 初期化済み辞書

def main():
    N = i2n()
    XY = ii2nnn(N)
    # n <= 50 なので、xy[i] → xy[j] の全ての組み合わせについて、距離を全探索できちゃう
    # 距離 dx, dy をkeyに、その距離の i, j ペアの数をvalueとしてカウント
    d = defaultdict(lambda: 0)
    for i in range(N):
        xi, yi = XY[i]
        for j in range(N):
            if i == j:
                continue
            xj, yj = XY[j]
            dxy = (xj - xi, yj - yi)
            d[dxy] += 1
    # 基本はコストN
    # max(value) だけコストを減らせる
    n = N - max(d.values())
    print(n)

main()


Fixed submission:
import sys
from collections import deque  # 双方向キュー
from collections import defaultdict  # 初期化済み辞書
from heapq import heapify, heappush, heappop, heappushpop  # プライオリティキュー
from bisect import bisect_left, bisect_right  # 二分探索
#import numpy as np  # 1.8.2
#import scipy  # 0.13.3

s2nn = lambda s: [int(c) for c in s.split(' ')]
ss2nn = lambda ss: [int(s) for s in ss]
ss2nnn = lambda ss: [s2nn(s) for s in ss]
i2s = lambda: sys.stdin.readline().rstrip()
i2n = lambda: int(i2s())
i2nn = lambda: s2nn(i2s())
ii2ss = lambda n: [sys.stdin.readline().rstrip() for _ in range(n)]
ii2nn = lambda n: ss2nn(ii2ss(n))
ii2nnn = lambda n: ss2nnn(ii2ss(n))

def main():
    N = i2n()
    xy = ii2nnn(N)
    if N == 1:
        print(1)
        return
    dic = defaultdict(lambda: 0)
    for i in range(N):
        for j in range(N):
            if i == j:
                continue
            dx = xy[i][0] - xy[j][0]
            dy = xy[i][1] - xy[j][1]
            if dx == 0 and dy == 0:
                continue
            dic[(dx, dy)] += 1
    n = N - max(dic.values())
    print(n)

main()

Buggy python submission (verdict: Runtime Error):
import sys
from collections import deque  # 双方向キュー
from collections import defaultdict  # 初期化済み辞書
from heapq import heapify, heappush, heappop, heappushpop  # プライオリティキュー
from bisect import bisect_left, bisect_right  # 二分探索
#import numpy as np  # 1.8.2
#import scipy  # 0.13.3

s2nn = lambda s: [int(c) for c in s.split(' ')]
ss2nn = lambda ss: [int(s) for s in ss]
ss2nnn = lambda ss: [s2nn(s) for s in ss]
i2s = lambda: sys.stdin.readline().rstrip()
i2n = lambda: int(i2s())
i2nn = lambda: s2nn(i2s())
ii2ss = lambda n: [sys.stdin.readline().rstrip() for _ in range(n)]
ii2nn = lambda n: ss2nn(ii2ss(n))
ii2nnn = lambda n: ss2nnn(ii2ss(n))

def main():
    N = i2n()
    xy = ii2nnn(N)
    dic = defaultdict(lambda: 0)
    for i in range(N):
        for j in range(N):
            if i == j:
                continue
            dx = xy[i][0] - xy[j][0]
            dy = xy[i][1] - xy[j][1]
            if dx == 0 and dy == 0:
                continue
            dic[(dx, dy)] += 1
    n = N - max(dic.values())
    print(n)

main()


Fixed submission:
import sys
from collections import deque  # 双方向キュー
from collections import defaultdict  # 初期化済み辞書
from heapq import heapify, heappush, heappop, heappushpop  # プライオリティキュー
from bisect import bisect_left, bisect_right  # 二分探索
#import numpy as np  # 1.8.2
#import scipy  # 0.13.3

s2nn = lambda s: [int(c) for c in s.split(' ')]
ss2nn = lambda ss: [int(s) for s in ss]
ss2nnn = lambda ss: [s2nn(s) for s in ss]
i2s = lambda: sys.stdin.readline().rstrip()
i2n = lambda: int(i2s())
i2nn = lambda: s2nn(i2s())
ii2ss = lambda n: [sys.stdin.readline().rstrip() for _ in range(n)]
ii2nn = lambda n: ss2nn(ii2ss(n))
ii2nnn = lambda n: ss2nnn(ii2ss(n))

def main():
    N = i2n()
    xy = ii2nnn(N)
    if N == 1:
        print(1)
        return
    dic = defaultdict(lambda: 0)
    for i in range(N):
        for j in range(N):
            if i == j:
                continue
            dx = xy[i][0] - xy[j][0]
            dy = xy[i][1] - xy[j][1]
            if dx == 0 and dy == 0:
                continue
            dic[(dx, dy)] += 1
    n = N - max(dic.values())
    print(n)

main()