#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;
int k;
cin>>k;
int x[k+1], y[k+1];
ll r[k+1];
for (int d=1;d<=k;d++)
cin>>x[d]>>y[d]>>r[d];
ll ans=0;
for (int i=1;i<=n;i++)
{
set<int> t;
map<int,vector<int>> ad, rm;
t.insert(1), t.insert(m), ad[1].push_back(0), rm[m].push_back(0);
for (int d=1;d<=k;d++)
{
if (abs(i-x[d])>r[d]) continue;
int z=sqrtl(r[d]*r[d]-1ll*(x[d]-i)*(x[d]-i));
int l=y[d]-z, r1=y[d]+z;
t.insert(l), t.insert(r1);
ad[l].push_back(d), rm[r1].push_back(d);
}
multiset<int> se;
int ls=1;
while (t.size())
{
int x=*t.begin();t.erase(x);
if (x>1)
ans+=1ll*(x-ls-1)*(k-*se.rbegin()), ls=x;
for (int y:ad[x])
se.insert(y);
ans+=(k-*se.rbegin());
for (int y:rm[x])
se.erase(se.find(y));
}
}
cout<<ans<<endl;
return 0;
}
