AtCoder agc001

agc001_a.py

n = int(input())
L = list(map(int, input().split()))
L.sort()
ans = 0
for i in range(0,2*n,2):
    ans += min(L[i], L[i+1])
print(ans)

agc001_b.py

#coding:utf-8

n, x = map(int, input().split())

def func(a, b):
    if a < b:
        if b%a == 0:
            return (b//a*2 - 1)*a
        else:
            q, mod = divmod(b,a)
            return 2*q*a + func(a, mod)
            # return 2*a + func(a, b-a)
    elif a > b:
        if a%b == 0:
            return (a//b*2 - 1)*b
        else:
            q, mod = divmod(a,b)#divmod : 商と余りを同時に取得できる
            return 2*q*b + func(mod, b)
            # return 2*b + func(a-b, b)#再帰回数が10000を超えるとエラー(20000000001, 4)など
    else:
        return a

if x == n/2:
    print(3*x)
else:
    print(x+(n-x)+func(x,n-x))