#include<iostream>
using namespace std;
typedef unsigned long long ull;
ull a,b,p,res;
int main()
{
    cin>>a>>b>>p;
    while(b)
    {
        if(b&1) res = (res + a)%p;
        b = b / 2; 
        a = (a * 2)%p;
    }
    cout<<res;
}

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

long long a, b, p, ans = 0;

int main ()
{
	cin >> a >> b >> p;
	while (b)
        {
		if (b & 1) 
                {
                      ans = (ans + a) % p;
                }
		a = (a * 2) % p;
		b >>= 1;
	}
	cout << ans % p;
}
```

```cpp
#include <bits/stdc++.h>
using namespace std;
#define LL long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
long long a , b , p , res;
int main()
{
    cin >> a >> b >> p;
    while ( b )
    {
        if ( b & 1 ) 
		{
			res = ( res + a ) % p;
		}
        b = b / 2; 
        a = ( a * 2 ) % p;
    }
    cout << res;
}
//菜鸟驿站
//老六专属

#include<bits/stdc++.h>
using namespace std;
long long a,b,p,ans=0;
int main(){
	cin >>a>>b>>p;
	while(b){
		if(b & 1) ans=(ans+a)%p;
		a=(a*2)%p;
		b>>=1;
	}
	cout<<ans%p;
}