#include<stdio.h>
#define nmax 100
int sol, *p[10],v[nmax],n,k,a,b;
void citire();
void afisare();
void rest();

int main()
{citire();
 rest();
 //rezolva();
 afisare();
 return 0;
 }

void afisare()
{freopen("divk.out","w",stdout);
 scanf("%ld",sol);
 fclose(stdout);
 }

void citire()
{int long i;
 freopen("divk.in","r",stdin);
 scanf("%ld%ld%ld%ld",&n,&k,&a,&b);
 for(i=1;i<=n;i++)
  scanf("%ld",&v[i]);
 }

void rest()
{int long i;
 for(i=1;i<=n;i++)
  p[v[i]%k][++p[v[i]%k][0]]=i;
 }

void rezolva()
{int long i,j,ls,ld;
 for(i=0;i<k;i++)
  for(j=2,ls=ld=1;j<=p[i][0];j++)
	sol=p[i][j];
 }