#include <cstdio>

 #include <cctype>

 #include <cstring>

 #include <algorithm>

 using namespace std;

 const int maxn = ;

 int L, S, T, M, pos[], a[maxn], f[maxn];

 int main() {

     scanf("%d %d %d %d", &L, &S, &T, &M);

     for (int i = ; i <= M; i++)

         scanf("%d", &pos[i]);

     sort(pos + , pos +  + M);

     for (int i = ; i <= M; i++) {

         if (pos[i] - pos[i - ] > T) {

             for (int j = M; j >= i; --j)

                 pos[j] -= pos[i] - pos[i - ] - T - (pos[i] - pos[i - ]) % T;

         }

     }

     for (int i = ; i <= M; i++)    a[pos[i]] = ;

     L = pos[M] + ;

     for (int i = ; i <= L; i++)    f[i] = ;

     for (int i = ; i < L; i++) {

         for (int j = S; j <= T; j++) {

             int arrive = min(L, i + j);

             f[arrive] = min(f[arrive], f[i] + a[arrive]);

         }

     }

     printf("%d\n", f[L]);

     return ;

 }