#include <iostream>
using namespace std;
int
g[21][21], n, f[21];
void
__read__()
{
cin >> n;
if( n == 0 )
{
cout << 0 << endl;
exit( 0 );
}
for( int i = 1; i <= n; i++ )
for( int j = 1; j <= i; j++ )
cin >> g[i][j];
}
void
__init__()
{
for( int i = 1; i <= n; i++ )
f[i] = 2123456789;
}
inline
int
_abs( int x )
{
if( x > 0 )
return x;
return -x;
}
void
__dfs__( int x, int y, int sum )
{
if( x < n )
{
__dfs__( x + 1, y, sum + g[x][y] );
__dfs__( x + 1, y + 1, sum + g[x][y] );
}
if( x == n )
if( _abs( sum + g[x][y] ) < _abs( f[y] ) )
f[y] = sum + g[x][y];
}
void
__outp__()
{
int min = 2123456789;
for( int i = 1; i <= n; i++ )
if( min > _abs( f[i] ) )
min = _abs( f[i] );
cout << min << endl;
}
int
main()
{
__read__();
__init__();
__dfs__( 1, 1, 0 );
__outp__();
return 0;
}