Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    for p1, p2, p3 in combinations(points, 3):
        z = (p3 - p1) / (p2 - p1)
        if z.imag == 0:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    try:
        return min(radiuses)
    except ValueError:
        return -1

print(solve())

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    for p1, p2, p3 in combinations(points, 3):
        z = (p3 - p1) / (p2 - p1)
        if z.imag == 0:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    radiuses = []
    from itertools import combinations
    err = 10 ** -6
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            d = abs(p - c)
            if d - r > err:
                break
        else:
            radiuses.append(r)
    
    print(min(radiuses))

solve()

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    radiuses = []
    from itertools import combinations
    err = 10 ** -7
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            d = abs(p - c)
            if d - r > err:
                break
        else:
            radiuses.append(r)
    
    print(min(radiuses))

solve()

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    radiuses = []
    from itertools import combinations
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = max(abs(p1 - c), abs(p2 - c))
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    print(min(radiuses))

solve()

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())

Buggy python submission (verdict: Runtime Error):
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    radiuses = []
    from itertools import combinations
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    print(min(radiuses))

solve()

Fixed submission:
def solve():
    from sys import stdin
    f_i = stdin
    
    N = int(f_i.readline())
    
    points = []
    for i in range(N):
        x, y = map(int, f_i.readline().split())
        points.append(x + y * 1j)
    
    from itertools import combinations
    radiuses = []
    
    for p1, p2 in combinations(points, 2):
        c = (p1 + p2) / 2
        r = abs(p1 - c)
        for p in points:
            if abs(p - c) > r:
                break
        else:
            radiuses.append(r)
    
    if radiuses:
        return min(radiuses)
    
    def circumcircle(a, b, c):
        n = (a - b) * abs(c) ** 2 + (b - c) * abs(a) ** 2 + (c - a) * abs(b) ** 2
        d = (a - b) * c.conjugate() + (b - c) * a.conjugate() + (c - a) * b.conjugate()
        return n / d # center of circumcircle
    
    err = 10 ** -7
    for p1, p2, p3 in combinations(points, 3):
        z1 = p3 - p1
        z2 = p2 - p1
        if z1.real * z2.imag == z1.imag * z2.real:
            continue
        
        c = circumcircle(p1, p2, p3)
        r = abs(p1 - c)
        for p in points:
            #if abs(p - c) > r:
            if abs(p - c) - r > err:
                break
        else:
            radiuses.append(r)
    
    return min(radiuses)

print(solve())