#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
signed main()
{
ios::sync_with_stdio(0);
cin.tie(NULL), cout.tie(NULL);
int n,m;
cin>>n>>m;
set<int> t[n+1];
map<int,vector<int>> ad[n+1], rm[n+1];
for (int i=1;i<=n;i++)
t[i].insert(1), t[i].insert(m), ad[i][1].push_back(0), rm[i][m].push_back(0);
int k;
cin>>k;
for (int d=1;d<=k;d++)
{
int x,y;
ll r;
cin>>x>>y>>r;
for (int i=x-r;i<=x+r;i++)
{
int z=sqrtl(r*r-1ll*(x-i)*(x-i));
int l=y-z, r=y+z;
t[i].insert(l), t[i].insert(r);
ad[i][l].push_back(d), rm[i][r].push_back(d);
}
}
ll ans=0;
for (int i=1;i<=n;i++)
{
multiset<int> se;
int ls=1;
while (t[i].size())
{
int x=*t[i].begin();t[i].erase(x);
if (x>1)
ans+=1ll*(x-ls-1)*(k-*se.rbegin()), ls=x;
for (int y:ad[i][x])
se.insert(y);
ans+=(k-*se.rbegin());
for (int y:rm[i][x])
se.erase(se.find(y));
}
}
cout<<ans<<endl;
return 0;
}
