#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
const long double EPS = 0.000000001;
const long long INF64 = 1000000000000000000;
const long long INF32 = 2000000000;
bool iss_ll(long long &__1, long long &__2) { return INF64 / __1 >= __2; }
bool iss_sqr(long long &__1) {
  long long __2 = sqrt((long double)__1);
  return __2 * __2 == __1;
};
bool iss_prime(long long __1) {
  for (long long i = 2; i * i <= __1; ++i)
    if (!(__1 % i)) return 0;
  return 1;
}
long long gcd(long long __1, long long __2) {
  while (__1 && __2)
    if (__1 > __2)
      __1 = __1 % __2;
    else
      __2 = __2 % __1;
  return __1 + __2;
}
long long lcm(long long &__1, long long &__2) {
  return __1 * __2 / (gcd(__1, __2));
}
void f(long long &a, long long &b) {
  if (0 == b || a == 0) return;
  if (a >= b * 2) {
    a = a % (2 * b);
    f(a, b);
  } else {
    if (b >= 2 * a) {
      b = b % (2 * a);
      f(a, b);
    }
  }
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  long long sum = 0;
  for (long long i = 0; i < n; ++i) {
    long long x;
    cin >> x;
    sum += abs(x);
  }
  cout << sum << "\n";
}
