If you are new to learning programming and do not know where to start, please try Problem A “Welcome to AtCoder” from practice contest. There you can find a sample code for each language.
Also, if you are not familiar with problems in programming contests, we recommend you to try some problems in “AtCoder Beginners Selection” (https://atcoder.jp/contests/abs).

This problem requires input, output, and a division where the fractional part is rounded up. Also, since the constraints are as large as \(10^{18}\), so you need to use a suitable type.

For positive integers \(A\) and \(B\), the value \(\frac{A}{B}\) rounded up equals \(\frac{A+B-1}{B}\) rounded down, so one can use this expression to find it. Alternatively, if \(A\) is divisible by \(B\), then the sought value is found as \(\frac{A}{B}\), and otherwise, \(\frac{A}{B} + 1\), rounded down.

If you use ceil of a decimal type, the dobule type in C++ does not have sufficient precision to find the correct answer, for example for Sample 3. (If you use long dobule, this time the answer will be correct.)

Regarding the type, using a 32-bit integer type will lead to an overflow, so you need to use 64-bit integer type (like long long).

Sample code (C++)

#include<bits/stdc++.h>
using namespace std;
int main(){
  long long a,b;
  cin>>a>>b;
  cout<<(a+b-1)/b<<endl;
}

Sample code (Python)

A, B = map(int, input().split())
print((A + B - 1) // B)