#include <stdio.h>

using namespace std;

int a[1000][1000];

void romb(int x, int y, int l, int n, int m) {
    int k = 0;
    x--; y--;

    for (int i = 0; i < l; i++) {
        for (int j = y-k; j <= y+k; j++) {
            if (j < 0) j++;
            else if (j >= m) break;

            a[x][j] = 1;
        }

        x++;
        k++;

        if (x >= n) break;
    }

    k-=2;

    for (int i = 0; i < l-1; i++) {
        for (int j = y-k; j <= y+k; j++) {
            if (j < 0) j++;
            else if (j >= m) break;
            a[x][j] = 1;
        }

        x++;
        k--;

        if (x >= n) break;
    }
}

int nrp(int p, int n, int m) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == 0) {
                p++;
            }
        }
    }

    return p;
}

void print(int n, int m) {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            printf("%d ", a[i][j]);
        }

        printf("\n");
    }
}
int main()
{
    freopen("romburi.in", "r", stdin);
    freopen("romburi.out", "w", stdout);

    int n, m, t;

    scanf("%d %d %d", &n, &m, &t);

    int x, y, l;

    for (int i = 0; i < t; i++) {
        scanf("%d %d %d", &x, &y, &l);

        romb(x, y, l, n, m);
    }

    fclose(stdin);

    int p = 0;

    printf("%d", nrp(p, n, m));

    fclose(stdout);

    return 0;
}