public static void main ( String [ ] args ) throws IOException {
  BufferedReader in = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  StringTokenizer stk = new StringTokenizer ( in . readLine ( ) ) ;
  int n = Integer . parseInt ( stk . nextToken ( ) ) ;
  int m = Integer . parseInt ( stk . nextToken ( ) ) ;
  int arr [ ] = new int [ n + 1 ] ;
  Arrays . fill ( arr , 0 ) ;
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    stk = new StringTokenizer ( in . readLine ( ) ) ;
    int a = Integer . parseInt ( stk . nextToken ( ) ) ;
    int b = Integer . parseInt ( stk . nextToken ( ) ) ;
    int c = Integer . parseInt ( stk . nextToken ( ) ) ;
    arr [ a ] += c ;
    arr [ b ] -= c ;
  }
  long ans = 0 ;
  for ( int i = 0 ;
  i < n + 1 ;
  i ++ ) {
    if ( arr [ i ] > 0 ) ans += arr [ i ] ;
  }
  System . out . println ( ans ) ;
}

public static void main ( String [ ] args ) throws IOException { BufferedReader in = new BufferedReader ( new InputStreamReader ( System . in ) ) ; StringTokenizer stk = new StringTokenizer ( in . readLine ( ) ) ; int n = Integer . parseInt ( stk . nextToken ( ) ) ; int m = Integer . parseInt ( stk . nextToken ( ) ) ; int arr [ ] = new int [ n + 1 ] ; Arrays . fill ( arr , 0 ) ; for ( int i = 0 ; i < m ; i ++ ) { stk = new StringTokenizer ( in . readLine ( ) ) ; int a = Integer . parseInt ( stk . nextToken ( ) ) ; int b = Integer . parseInt ( stk . nextToken ( ) ) ; int c = Integer . parseInt ( stk . nextToken ( ) ) ; arr [ a ] += c ; arr [ b ] -= c ; } long ans = 0 ; for ( int i = 0 ; i < n + 1 ; i ++ ) { if ( arr [ i ] > 0 ) ans += arr [ i ] ; } System . out . println ( ans ) ; }
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