#include<bits/stdc++.h>
using namespace std;
int main
{
int a[4][4]={1,2,-3,-4,0,-12,-13,14,-21,23,0,-24,-31,32,-33,0}
int i,j,s=0;
for(i=1;i<4;i++)
for(j=0;j<4;j++)
{
if (a[i][j]<0) continue;
if (a[i][j]==0) break;
s+=a[i][j];
}
cout<<s<<endl;
return 0;
}