#include <stdio.h>
#define N 2000
#define INF 0x3f3f3f3f
int min(int a, int b) { return a < b ? a : b; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int xx[N * 2], xx_[N * 2], yy[N * 2];
void sort(int *ii, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;
while (j < k)
if (xx[ii[j]] == xx[i_])
j++;
else if (xx[ii[j]] < xx[i_]) {
tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
i++, j++;
} else {
k--;
tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
}
sort(ii, l, i);
l = k;
}
}
int main() {
static int ii[N * 2], dp[N + 1][2];
int n, m, k, i, i_, j, c;
scanf("%d%d%d", &n, &m, &k), k = n - k;
for (i = 0; i < n * 2; i++) {
scanf("%d", &xx[i]);
ii[i] = i;
}
sort(ii, 0, n * 2);
for (i = 0; i < n * 2; i++)
xx_[ii[i]] = i;
for (i = 0; i + 1 < n * 2; i++)
yy[i] = xx[ii[i + 1]] - xx[ii[i]];
for (c = 0; c <= k; c++)
dp[c][0] = dp[c][1] = INF;
dp[0][0] = 0;
for (i = 0; i + 1 < n * 2; i++)
if ((ii[i] & 1) == 0) {
if ((ii[i] ^ ii[i + 1]) == 1)
for (c = k; c >= 0; c--)
dp[c][0] = min(dp[c][0], c == 0 ? INF : dp[c - 1][0] + yy[i]);
else if ((ii[i + 1] & 1) == 0) {
for (i_ = i; (ii[i_] & 1) == 0; i_ = j) {
j = xx_[ii[i_] ^ 1] - 1;
for (c = k; c >= 0; c--) {
dp[c][0] = min(dp[c][0], dp[c][1]);
dp[c][1] = c == 0 ? INF : min(min(dp[c - 1][0] + yy[i_], dp[c - 1][1]) + yy[j], INF);
}
}
for (c = k; c >= 0; c--)
dp[c][0] = min(dp[c][0], dp[c][1]), dp[c][1] = INF;
}
}
printf("%d\n", m - dp[k][0]);
return 0;
}
