int main(){
    int n,a,b,result=0,i=1,max=0;
    scanf("%d",&n);
    while(i<=n){
    scanf("%d%d",&a,&b);
    if(a>=90&&a<=140&&b>=60&&b<=90){
    result+=1;
    i++;
    }else{
    if(result>max){
    max=result;
    result=0;
    i++;}
    else{
    result=0;
    i++;}
    }
    }
    if(result>max){
       max=result;}
    printf("%d",max);
    return 0;
}
    
    

    