Polygon area

n = int(input())

def cross_product(a, b):
    return a[0]*b[1] - a[1]*b[0]

tot = 0
x0, y0 = [int(x) for x in input().split()]
x_0, y_0 = x0, y0
for _ in range(n-1):
    x_1, y_1 = [int(x) for x in input().split()]
    tot += x_0*y_1 - x_1*y_0
    x_0, y_0 = x_1, y_1

tot += x_0*y0 - x0*y_0

print(abs(tot))

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED