#include <cstdio>
#define int long long
int read()
{
	int x=0,f=1;char c;
	while((c=getchar())<'0' || c>'9') {if(c=='-') f=-1;}
	while(c>='0' && c<='9') {x=(x<<3)+(x<<1)+(c^48);c=getchar();}
	return x*f;
}
int n,m,k,p;
int qkpow(int a,int b)
{
	int r=1;
	while(b>0)
	{
		if(b&1) r=r*a%p;
		a=a*a%p;
		b>>=1;
	}
	return r;
}
signed main()
{
	n=read();k=read();m=read();p=read();
	int ans=n%p*qkpow(m,k-1)%p-
	qkpow(m,k-2)*(k-1)%p*((m+1)*m/2%p)%p;
	printf("%lld\n",(ans+p)%p);
}