//This code is a exercise of SPOJ http://br.spoj.pl/
//This code was developed by Victor Mello Floriano


#include <stdio.h>
#include <stdlib.h>

int main()
{
int x[50];
int quant;
scanf("%d",&quant);

int i, soma=0;

for(i = 0;i<quant;i++)
{
    scanf("%d",&x[i]);
    if(x[i]<0){x[i]=x[i]*-1;}
    soma = soma + x[i];
}

printf("%d",soma);


}