What is happening?

Why is here the runtime error on the 6 test?

What test is 6?

#include <iostream>

#include <cmath>

using namespace std;

void ghjkl(long double p)

{cout << fixed;

cout.precision(4);

cout << p << endl;}

int main() {

long double a[1000]={-1.0};

long long i=0;

while(cin)

{cin >> a[i];

i++;}

i=i-2;

long double b[1000];

for(int k=0; k<1000; k++)

{b[k]=sqrt(a[k]);}

for(int m=i; m>=0; m--)

{ghjkl(b[m]);}

return 0;

}

*Edited by author 24.03.2021 16:53*

*Edited by author 24.03.2021 16:54*