my program is throwing error Process terminated with status -1073741819 . its also not taking input properly( less than expected)

```
#include <iostream>
#include <bits/stdc++.h>
using namespace std;
int main()
{
int tests,n,m,sum=0;
vector <int> lengths;
cin >> tests;
int min_length(n);
for (int i=0;i<tests;i++)
{
cin >> n >> m;
for(int j=0;j<n;j++)
{
for(int k=0;k<m;k++)
{
cin >> lengths(k); \ this line is for taking input
}
min_length(j)={*min_element(lengths.begin(), lengths.end())}; \ this is for minimum element
}
sum = accumulate(min_length, min_length+n, sum);
cout << sum;
sum=0;
}
}
```