**Link to the problem**: https://cses.fi/problemset/task/1620

**My Approach**: If it is possible to make **m** products in **d** days then it is also possible to make **m** products in **d+1** days, and if it is not possible to make **m** products in **d** days then it is also not possible to make **m** products in **d-1** days. Using this property we can apply binary search to find the smallest number of days in which we can make the given number of products. As for the upper bound, the worst case will be when I have to make 10^9 products and I have only one machine which takes 10^9 days to make one product, so the total time taken in this case will be 10^18.

**Following is my code**:

```
#include <bits/stdc++.h>
using namespace std;
#define FASTIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using ll = long long;
const int mxn = 2e5 + 5;
const ll inf = (1LL<<62);
int n; ll t, arr[mxn];
bool check(ll d)
{
ll cnt = 0;
for(int i=0; i<n; i++)
cnt += (d/arr[i]);
if(cnt < t) return false;
return true;
}
ll findDays()
{
ll low = 1, high = 1e18+5, days = 0;
while(low <= high)
{
ll mid = low+(high-low)/2;
if(check(mid))
{
days = mid;
high = mid-1;
}
else
low = mid+1;
}
return days;
}
int main()
{
FASTIO
cin >> n >> t;
for(int i=0; i<n; i++) cin >> arr[i];
cout << findDays() << "\n";
return 0;
}
```

The above code works for all the test cases except for two, where it gives a WA.

Following is one of them:

```
25 1000000000
1000000000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
```

My code gives the answer as 768614336414205720 whereas the correct answer is 41666667.

Can anybody please point out the error in my code which leads to such an answer?