<pre><code class="lang-cpp">#include &lt;iostream&gt;
using namespace std;

int main(){
 int n;
 cout&lt;&lt;"Enter: ";
 cin&gt;&gt;n;
 int m = n, mask = 0;
 if (n == 0){
 cout&lt;&lt;1;
 }else{
 while(m!=0){
 mask = (mask&lt;&lt;1) | 1;
 m=m&gt;&gt;1;
 }
 int ans = (~n) &amp; mask;
 cout&lt;&lt;ans;

 }

}
</code></pre>

```cpp
#include <iostream>
using namespace std;

int main(){
 int n;
 cout<<"Enter: ";
 cin>>n;
 int m = n, mask = 0;
 if (n == 0){
 cout<<1;
 }else{
 while(m!=0){
 mask = (mask<<1) | 1;
 m=m>>1;
 }
 int ans = (~n) & mask;
 cout<<ans;

 }

}
```

#4 Leetcode (Complement of Base 10 Integer)