#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;
int N,M,L[100010],R[100010];
ll A,P[100010];


int main(){
    cin >> N >> M >> A;
    for(int i=0;i<M;i++){
        cin >> L[i] >> R[i] >> P[i];
    }
    ll ans = 0;
    for(int S=0;S<(1<<(N+1));S++){
        ll now = -A*(__builtin_popcount(S)-2);
        if(!(S&(1<<0)) || !(S&(1<<N))) continue;
        for(int i=0;i<M;i++){
            if(!(S&(1<<(L[i]-1))) || !(S&(1<<(R[i])))) continue;
            bool judge = true;
            for(int j=L[i];j<R[i];j++){
                if(S&(1<<j)){
                    judge = false;
                    break;
                }
            }
            if(judge) now += P[i];
        }
        ans = max(ans,now);
    }
    cout << ans << endl;
}