#include <fstream>
#include <algorithm>
#include <cmath>
#define N 1005
using namespace std;
ifstream fin("romburi.in");
ofstream fout("romburi.out");
bool a[N][N];
int n,m,p, x,y,l, i,j;
int nr;
int xc,yc,d;
int main() {

  fin>>n>>m>>p;
  while(p>0)
  {
      p--;
      fin>>x>>y>>l;
      a[x][y]=1;
      xc=x;
      yc=y;
      d=2*l-1;
      for(i=1;i<=d-2;i+=2)
      {
          for(j=yc; j<=yc+i-1;j++)
            if(xc>=1 && xc<=n && j>=1 && j<=m)
              a[xc][j]=1;
          yc--;
          xc++;
      }
      for(i=d;i>=1;i-=2)
      {
          for(j=yc; j<=yc+i-1;j++)
            if(xc>=1 && xc<=n && j>=1 && j<=m)
              a[xc][j]=1;
        yc++;
        xc++;
      }

  }

  for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
      if(a[i][j]==0)nr++;
  fout<<nr;
  return 0;
}