//Sylwia Sapkowska
#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;
void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef LOCAL
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
#define int long long
typedef pair<int, int> T;
const int oo = 1e18, oo2 = 1e9+7, K = 30;
const int mod = 998244353;
void solve(){
int n, d, tt; cin >> n >> d >> tt;
vector<int>t(n+1);
for (int i = 1; i<=n; i++) cin >> t[i];
vector<int>prev(n+1, oo);
stack<int>s;
for (int i = 1; i<=n; i++){
s.push(i);
while ((int)s.size() && s.top() - t[s.top()] < i - tt) s.pop();
if ((int)s.size()) prev[i] = s.top();
}
debug(prev);
// return;
vector dp(n+1, vector<int>(d+2, oo));
vector C(n+1, vector<int>(n+1, oo));
for (int j = 0; j<=n; j++){
//stawiamy przeszkode miedzy indeksem j a j+1
int cnt = 0;
for (int i = j+1; i<=n; i++){
if (prev[i] > j) cnt++;
C[j][i] = cnt;
debug(j, i, C[j][i]);
}
}
dp[0][0] = 0;
for (int i = 1; i<=n; i++){
dp[i][1] = C[0][i];
debug(dp[i][1]);
for (int cd = 1; cd <= d+1; cd++){
for (int j = 0; j<i; j++){
dp[i][cd] = min(dp[i][cd], dp[j][cd-1] + C[j][i]);
}
debug(i, cd, dp[i][cd]);
}
}
cout << dp[n][d+1] << "\n";
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while (t--) solve();
return 0;
}
