local n,m,q=io.read("n","n","n")
local a,b,c,d={},{},{},{}
for i=1,q do
    a[i],b[i],c[i],d[i]=io.read("n","n","n","n")
end

local t={}
for i=1,10 do
    t[i]={}
end
for i=1,m do
    table.insert(t[1],{i})
end

for i=1,n-1 do
    for j,_ in pairs(t[i]) do
        local x=t[i][j]
        local p=x[#x]
        for k=p,m do
            local U={table.unpack(x)}
            table.insert(U,k)
            table.insert(t[i+1],U)
        end
    end
end

local answer=0
for _,T in pairs(t[n]) do
    local total=0
    for i=1,q do
        if T[b[i]]-T[a[i]]==c[i] then
            total=total+d[i]
        end
    end
    answer=math.max(answer,total)
end
print(answer)