#include <iostream>
#define N 3//height,width,depth
int count=0;
int box;
int main() {
	scanf("%d",&box);
	int boxcapa[box][N];
	for(int i=0;i<box;i++){
		for(int j=0;j<N;j++){
			scanf("%d",&boxcapa[i][j]);
			if(i>=1){
				if(boxcapa[i-1][j-1]>boxcapa[i][j]||boxcapa[i-1][j-1]<boxcapa[i][j]){
					count++;
				}
				
			}

	  }
	}
	printf("%d",count/3);

}