import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int m,n,a,b,l,x,y,k,i,j;
		int[] [] diat=null;
		while(in.hasNext()) {
			n = in.nextInt();
			m = in.nextInt();
			diat = new int[n][n];
			for(i=0;i<n;i++) {
				for(j=0;j<n;j++) {
					diat[i][j]=100;
				}
			}
			for(int h=0;h<m;h++) {
				a=in.nextInt();
				b=in.nextInt();
				l=in.nextInt();
				diat[a-1][b-1]=l;
				diat[b-1][a-1]=l;		
			}
			for(k=0;k<n;k++) {
				for(i=0;i<n;i++) {
					for(j=0;j<n;j++) {
					if(diat[i][j]>(diat[i][k]+diat[k][j])){
						diat[i][j]=diat[i][k]+diat[k][j];
					}
				}
			}	
		}
			x=in.nextInt()-1;
			y=in.nextInt()-1;
			if(diat[x][y]!=100)
				System.out.println(diat[x][y]);
			else
				System.out.println("No path");
	}

}
}

/**************************************************************
	Problem: 2044
	User: admin
	Language: Java
	Result: Accepted
	Time:2167 ms
	Memory:40008 kb
****************************************************************/