#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <cstdlib>
using namespace std;

const long long MAXN = 300;
const long long INF = 1e15;

inline long long read() {
	long long x = 0, f = 1;
	char ch = getchar();
	while (!isdigit(ch)) {
		if (ch == '-') f = -1;
		ch = getchar();
	}
	while (isdigit(ch)) {
		x = x * 10 + ch - '0';
		ch = getchar();
	}
	return x * f;
}

struct node {
	long long r, p;
	bool operator < (const node &a) const {
		return r < a.r;
	}
} a[MAXN];

long long k, d;
long long dp[MAXN][MAXN]; // dp[j][i][cnt]
long long DD[MAXN][2], sum[MAXN][2];

int main() {
	d = read(); k = read();
	for (long long i = 1; i <= d; i++) {
		a[i].r = read();
		a[i].p = read();
		DD[a[i].r][0] = a[i].r * a[i].p;
		DD[a[i].r][1] = a[i].p;
	}
	sort(a + 1, a + 1 + d);
	sum[0][0] = DD[0][0]; 
	sum[0][1] = DD[0][1];
	for (long long i = 1; i <= 255; i++) {
		for (long long j = 0; j < 2; j++)
			sum[i][j] = sum[i - 1][j] + DD[i][j];
	}
	for (long long j = 0; j <= 255; j++) {
		for (long long kk = 1; kk <= 256; kk++)
			dp[j][kk] = INF;
	}
	for (long long i = 0; i <= 255; i++) {
		dp[i][1] = 0;
		for (long long j = 1; j <= d; j++) {
			dp[i][1] += a[j].p * (a[j].r - i) * (a[j].r - i);
		}
	}
	for (long long cnt = 2; cnt <= k; cnt++) {
		for (long long i = 0; i <= 255; i++) {
			for (long long j = 0; j < i; j++) {
				long long A = (2 * j - 2 * i) * (sum[255][0] - sum[(i + j) / 2][0]) + (i * i - j * j) * (sum[255][1] - sum[(i + j) / 2][1]);
				dp[i][cnt] = min(dp[i][cnt], dp[j][cnt - 1] + A); 
			}
		}
	}
	long long minn = INF;
	for (long long i = 0; i <= 255; i++) {
		minn = min(minn, dp[i][k]);
	}
	printf("%lld\n", minn); 
	return 0;
}