#include <bits/stdc++.h>
using namespace std;
int n, m, k, p[105], w[105], e[105], mem[105][105][2][2005];
int dp(int l, int r, int E, int t) {
if (l < 1 || r > m)
return 0;
int &ret = mem[l][r][E][t];
if (~ret)
return ret;
ret = 0;
if (!E) {
ret = max(ret, dp(l - 1, r, 0, min(2001, abs(p[l] - p[l - 1]) + t)) + (t < e[l] ? w[l] : 0));
ret = max(ret, dp(l, r + 1, 1, min(2001, abs(p[l] - p[r + 1]) + t)) + (t < e[l] ? w[l] : 0));
}
else {
ret = max(ret, dp(l - 1, r, 0, min(2001, abs(p[r] - p[l - 1]) + t)) + (t < e[r] ? w[r] : 0));
ret = max(ret, dp(l, r + 1, 1, min(2001, abs(p[r] - p[r + 1]) + t)) + (t < e[r] ? w[r] : 0));
}
return ret;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> k >> m;
for (int i = 1; i <= m; i++) {
cin >> p[i] >> w[i] >> e[i];
}
p[m + 1] = n + 100;
memset(mem, -1, sizeof mem);
int ans = 0;
for (int i = 1; i <= m; i++) {
ans = max(ans, dp(i, i, 0, abs(p[i] - k)));
}
cout << ans << endl;
return 0;
}
