#include <bits/stdc++.h>
using namespace std;
#define int long long
#define task "task"
#define fi first
#define se second
#define pb push_back
#define FOR(i, a, b) for(int i = (a), _b = (b); i <= _b; i ++)
#define FORD(i, a, b) for(int i = (a), _b = (b); i >= _b; i --)
#define bit(x, i) ((x >> i) & 1)
#define oo 1e18
#define all(v) v.begin(), v.end()
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
// mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());
// ll rand(ll l, ll r) { assert(l <= r); return uniform_int_distribution<ll>(l, r)(rd); }
const int N = 2e3 + 5;
const int mod = 1e9 + 7;
const int base = 31;
int n, m, k, dp[N][N][2], val[N], ans = 0, sz[N], f[N];
vector<pii> g[N];
vector<pii> v;
bool vis[N];
void dfs(int u, int p){
sz[u] = vis[u] = 1;
dp[u][1][1] = val[u];
for(auto [v, w] : g[u]) if(v != p){
dfs(v, u);
FORD(i, sz[u], 0)
FOR(j, 1, min(sz[v], k - i)){
dp[u][i + j][0] = max(dp[u][i + j][0], dp[u][i][0] + max(dp[v][j][0], dp[v][j][1]));
if(i > 0) dp[u][i + j][1] = max({dp[u][i + j][1], dp[u][i][1] + dp[v][j][0], dp[u][i][1] + dp[v][j][1] + w});
}
sz[u] += sz[v];
}
}
void solve(){
cin>>n>>m>>k;
FOR(i, 1, n){
int x, y; cin>>x>>y;
v.pb({x, i});
v.pb({y, -i});
}
sort(v.begin(), v.end());
FOR(i, 1, v.size() - 1){
int len = v[i].fi - v[i - 1].fi;
if(v[i - 1].se > 0 && v[i].se > 0) val[v[i - 1].se] += len;
if(v[i - 1].se < 0 && v[i].se < 0) val[-v[i].se] += len;
if(v[i - 1].se > 0 && v[i].se < 0){
int x = -v[i].se, y = v[i - 1].se;
if(x == y){
val[x] += len;
continue;
}
g[x].pb({y, len});
g[y].pb({x, len});
}
if(v[i - 1].se < 0 && v[i].se > 0)
ans += len;
}
FOR(i, 1, n) if(!vis[i]){
dfs(i, 0);
FORD(j, k, 0)
FOR(o, 1, sz[i])
f[j + o] = max(f[j + o], f[j] + max(dp[i][o][0], dp[i][o][1]));
}
cout<<ans + f[k] + m - v[v.size() - 1].fi + v[0].fi;
}
signed main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int nTest = 1;
// cin>>nTest;
while(nTest --) solve();
// cerr << "\nTime: " << 1.0 * clock() / CLOCKS_PER_SEC << "s\n";
return 0;
}
/*
*/
