#include <bits/stdc++.h>
using namespace std;
//int d[4][2]={{1,0},{0,1},{-1,0},{0,-1}};
int main(){
    int n,m,x[105],y[105],c[105],ant=0;
    cin>>n>>m;
    for(int i=0;i<n;i++){
    	cin>>x[i]>>y[i]>>c[i];
	}
	for(int i=0;i<5;i++){
		if(x[i]==x[i+1]&&y[i]+1==y[i+1]&&c[i]==c[i+1]){
			ant++;
			continue;
		}
		if(y[i]==y[i+1]&&x[i]+1==x[i+1]&&c[i]==c[i+1]){
			ant++;
			continue;
		}
		if(x[i]==x[i+1]&&y[i]+1==y[i+1]&&c[i]!=c[i+1]){
			c[i]=c[i+1];
			if(x[i]==x[i+1]&&y[i]+1==y[i+1]&&c[i]==c[i+1]){
				ant=ant+2;
			}
			if(y[i]==y[i+1]&&x[i]+1==x[i+1]&&c[i]==c[i+1]){
				ant=ant+2;
			}
		}
		if(y[i]==y[i+1]&&x[i]+1==x[i+1]&&c[i]!=c[i+1]){
			c[i]=c[i+1];
			if(x[i]==x[i+1]&&y[i]+1==y[i+1]&&c[i]==c[i+1]){
				ant=ant+2;
			}
			if(y[i]==y[i+1]&&x[i]+1==x[i+1]&&c[i]==c[i+1]){
				ant=ant+2;
			}
		}
		else{
			cout<<-1;
			return 0;
		}
	}
	if(ant==0){
		cout<<-1;
		return 0;
	}
	cout<<ant;
    return 0;
}