这份代码为什么运行出来有点像system("cls")的清空不完全？？？

#include <bits/stdc++.h>
#include <windows.h>
#include <conio.h>
using namespace std;
int n=30,m=55;
char c[105][105];
void plane(){
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			c[i][j]='.';
		}
	}
	int mid=m/2+1;
	c[n][mid]='_',c[n][mid-1]='|',c[n][mid+1]='|';
	c[n-1][mid+2]='_',c[n-1][mid+3]='_',c[n-1][mid+4]='_',c[n-1][mid+5]='\\';
	c[n-1][mid-2]='_',c[n-1][mid-3]='_',c[n-1][mid-4]='_',c[n-1][mid-5]='/';
	c[n-2][mid+4]='\\',c[n-2][mid-4]='/',c[n-2][mid-2]='p',c[n-2][mid-1]='l',c[n-2][mid]='a',c[n-2][mid+1]='n',c[n-2][mid+2]='e';
	c[n-3][mid+3]='_',c[n-3][mid+2]='\\',c[n-3][mid-3]='_',c[n-3][mid-2]='/';
	c[n-4][mid+1]='\\',c[n-4][mid]='|',c[n-4][mid-1]='/';
}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	system("mode 60,40");
	plane();
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cout<<c[i][j];
		}
		cout<<"\n";
	}
	while(1){
		for(int i=1;i<=n;i++){
			for(int j=1;j<=m;j++){
				cout<<c[i][j];
			}
			cout<<"\n";
		}
		Sleep(200);
		system("cls");
	}
	return  0;
}