#include<bits/stdc++.h>
#define reg register int
#define il inline
#define fi first
#define se second
#define mk(a,b) make_pair(a,b)
#define numb (ch^'0')
#define pb push_back
#define solid const auto &
#define enter cout<<endl
#define pii pair<int,int>
using namespace std;
typedef long long ll;
template<class T>il void rd(T &x){char ch;x=0;bool fl=false;while(!isdigit(ch=getchar()))(ch=='-')&&(fl=true);for(x=numb;isdigit(ch=getchar());x=x*10+numb);(fl==true)&&(x=-x);
}
template<class T>il void output(T x){if(x/10)output(x/10);putchar(x%10+'0');}
template<class T>il void ot(T x){if(x<0) putchar('-'),x=-x;output(x);putchar(' ');}
template<class T>il void prt(T a[],int st,int nd){for(reg i=st;i<=nd;++i) ot(a[i]);putchar('\n');}namespace Miracle{
const int N=55;
const int P=N*N;
const int inf=0x3f3f3f3f;
int n,m,h;
int s,t;
struct node{int nxt,to;int w;
}e[2*(P+P+N*N)];
int hd[P],cnt=1;
void add(int x,int y,int z){e[++cnt].nxt=hd[x];e[cnt].to=y;e[cnt].w=z;hd[x]=cnt;e[++cnt].nxt=hd[y];e[cnt].to=x;e[cnt].w=0;hd[y]=cnt;
}
int d[P];
int q[P],l,r;
int ans;
int dfs(int x,int flow){int res=flow;if(x==t) return flow;for(reg i=hd[x];i&&res;i=e[i].nxt){int y=e[i].to;if(d[y]==d[x]+1&&e[i].w){int k=dfs(y,min(res,e[i].w));if(!k) d[y]=0;res-=k;e[i].w-=k;e[i^1].w+=k;}   }return flow-res;
}
bool bfs(){memset(d,0,sizeof d);l=1,r=0;q[++r]=s;d[s]=1;while(l<=r){int x=q[l++];for(reg i=hd[x];i;i=e[i].nxt){int y=e[i].to;if(e[i].w&&!d[y]){d[y]=d[x]+1;q[++r]=y;if(y==t) return true;}}}return false;
}
int num(int x,int y){return (x-1)*(h+1)+y+1;
}
int main(){rd(n);rd(h);rd(m);ans=n*h*h;s=0;t=num(n,h)+1;int tot=t;for(reg i=1;i<=n;++i){add(s,num(i,0),inf);for(reg j=0;j<h;++j){add(num(i,j),num(i,j+1),h*h-j*j);}}int l,r,x,c;for(reg i=1;i<=m;++i){rd(l);rd(r);rd(x);rd(c);if(x<h){++tot;add(tot,t,c);for(reg j=l;j<=r;++j){add(num(j,x+1),tot,inf);}}}int flow=0;while(bfs()){while(flow=dfs(s,inf)) ans-=flow;}ot(ans);return 0;
}}
signed main(){Miracle::main();return 0;
}/*Author: *Miracle*
*/