kek

#include<bits/stdc++.h>

using namespace std;

const int INF = 1e9;

int prev(int a, int b) {
    return a < b ? a + 1 : a - 1;
}

int *cpos, *clifetime;

int dist(int a, int b) {
    return abs(cpos[a] - cpos[b]);
}

int cash[1 << 10][1 << 10];
void clear_cash() {
    for (int i = 0; i < (1 << 10); ++i) {
        for (int j = 0; j < (1 << 10); ++j) {
            cash[i][j] = (i != j) * (-1);
        }
    }
}

int bust(int a, int b) {
    if (cash[a][b] != -1) {
        return cash[a][b];
    }
    int x = bust(prev(a, b), b), dx = dist(prev(a, b), a),
        y = bust(b, prev(a, b)), dy = dist(b, a);
    cash[a][b] = INF;
    if (x != INF && x + dx <= clifetime[a]) {
        cash[a][b] = min(cash[a][b], x + dx);
    }
    if (y != INF && y + dy <= clifetime[a]) {
        cash[a][b] = min(cash[a][b], y + dy);
    }
    return cash[a][b];
}

int main(){

    clear_cash();

    int n;
    cin >> n;

    cpos = new int[n], clifetime = new int[n];
    for (int i = 0; i < n; ++i) {
        cin >> cpos[i] >> clifetime[i];
    }

    int res = min(bust(0, n - 1), bust(n - 1, 0));
    if (res == INF) {
        cout << "No solution";
    } else {
        cout << res;
    }

}