#include <cstdio>
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <cstdlib>
#include <cmath>
#include <set>
#include <map>
#include <vector>
#include <cstring>

#define INF 100000000L
using namespace std;
int n,ml,md;
int a[1005][1005];

struct node{
	int x,y,w;
};
int d[1005];

 
int main(){
	
	
	while(cin >>  n >> ml >> md){
		vector<node> vec;
	
		for(int i = 0 ;i < ml;i++){
			node a;
			scanf("%d%d%d",&a.x,&a.y,&a.w);
			vec.push_back(a);		
		}
		
		for(int i = 0;i < md;i++){
			node a;
			scanf("%d%d%d",&a.y,&a.x,&a.w);
			a.w = -a.w;
			vec.push_back(a);  
		}

		for(int i = 1;i <= n;i++){
			d[i] = INF;		
		}
		
		d[1] = 0;
		
		int len = vec.size();
		
		for(int k = 0;k < n;k++){
			for(int i = 1;i +1 <= n;i++){
				if(d[i+1] < INF) {
					d[i] = min(d[i],d[i+1]);//如果第i+1个已经有了最大的距离，那么第i个的最大距离就只会到i+1的最大距离 
				}
			}
			for(int i = 0;i < len;i++){
				if(d[vec[i].x] < INF){
					d[vec[i].y] = min(d[vec[i].x]+vec[i].w,d[vec[i].y]);// 
				}
			}
		}
		int ans = d[n];
		
		if(d[1] < 0){//有负环 
			ans = -1;
		}
		else if(ans == INF)
		{
			ans = -2;
		}
		cout << ans << endl;
	} 
	return 0;
}