Let us split into cases as follows.

If \(A>B\)

Obviously the answer is \(0\).

If \(A \leq B\)

\((B-A+1)\) integers are between \(A\) and \(B\) (inclusive): \(A,A+1, \ldots, \) and \(B\).

Therefore, one can obtain AC with the program like this.

Sample code (Python)

A,B = map(int,input().split())
if A>B:
    print(0)
else:
    print(B-A+1)

Note that we can avoid using a conditional branch as follows.

Sample code (C++)

#include<bits/stdc++.h>
using namespace std;

int main(){
	int A,B; cin >> A >> B;
	cout << max(0,B-A+1) << endl;
}