请问这个是出现什么低级错误了吗？麻烦各位师傅看一下。

#include <iostream>
#include <iomanip>
#include <math.h>
using namespace std;
int main()
{
	int q,c,e,r,t,y,u,i,o,p,l,k,j,h,M,N,n;
	int x[]={1,2,3,4,5,6,7};
	cin>>q>>c>>endl>>e>>r>>endl>>t>>y>>endl>>u>>i>>endl>>o>>p>>endl>>l>>k>>endl>>j>>h;
	x1=q+c;x2=e+r;x3=t+y;x4=u+i;x5=o+p;x6=l+k;x7=j+h;
	N=1;n=1;
	while (n<=7)
	{if (xn>=8)
	N++;
	n++;
	}
	M=max{z,x,c,v,b,n,m}
	if(n==0)cout<<"0";
	else cout<<M;
	
	return 0;
}