#include <bits/stdc++.h>
using namespace std;
const int N = 2000 + 10,
MAX = 1'000'000'000;
int n, m, k;
int s[N], t[N];
int type[N << 1], id[N << 1];
int nxt[N], deg[N];
int cost1[N], cost2[N];
int f[N][N][2];
int answer[N];
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i) cin >> s[i] >> t[i];
vector<int> rrh(s + 1, s + n + 1);
rrh.insert(rrh.end(), t + 1, t + n + 1);
sort(rrh.begin(), rrh.end());
rrh.erase(unique(rrh.begin(), rrh.end()), rrh.end());
rrh.insert(rrh.begin(), 0);
for (int i = 1; i <= n; ++i) {
s[i] = upper_bound(rrh.begin() + 1, rrh.end(), s[i]) - rrh.begin() - 1;
t[i] = upper_bound(rrh.begin() + 1, rrh.end(), t[i]) - rrh.begin() - 1;
type[s[i]] = 1;
id[s[i]] = id[t[i]] = i;
}
for (int i = 2; i < (int)rrh.size(); ++i) {
int idI = id[i], idJ = id[i - 1];
if (!type[i]) {
if (!type[i - 1] || idJ == idI) cost1[idI] += rrh[i] - rrh[i - 1];
else {
cost2[idI] += rrh[i] - rrh[i - 1];
nxt[idJ] = idI;
deg[idI] += 1;
}
} else {
if (type[i - 1]) cost1[idJ] += rrh[i] - rrh[i - 1];
}
}
for (int i = 0; i <= n; ++i) {
for (int j = 0; j <= k; ++j) f[i][j][0] = f[i][j][1] = MAX;
}
fill(answer + 1, answer + n + 1, MAX);
auto cal = [&](int x) {
f[x][0][0] = cost1[x];
f[x][1][1] = 0;
while (nxt[x]) {
int pre = x; x = nxt[x];
for (int i = 0; i <= k; ++i) {
{ // no key
auto& ret = f[x][i][0];
ret = min(ret, f[pre][i][0] + cost2[x] + cost1[x]);
ret = min(ret, f[pre][i][1] + cost2[x] + cost1[x]);
}
if (i) { // have key
auto& ret = f[x][i][1];
ret = min(ret, f[pre][i - 1][0] + cost2[x]);
ret = min(ret, f[pre][i - 1][1]);
}
}
}
for (int i = k; i >= 0; --i) {
int value = MAX;
for (int j = i; j >= 0; --j) {
value = min(value, answer[i - j] + min(f[x][j][0], f[x][j][1]));
}
answer[i] = value;
}
};
for (int i = 1; i <= n; ++i) {
if (!deg[i]) cal(i);
}
cout << m - *min_element(answer, answer + k + 1) << "\n";
}
