#include using namespace std; const int maxn = 1e3 + 5; int main() { int n, m, price[maxn], X[maxn], Y[maxn]; cin >> n >> m; for (int i = 0; i > price[i]; for (int i = 0; i > X[i] >> Y[i]; sort(price, price + n); int ans = 0; int vis[maxn]; memset(vis, 0, sizeof(vis)); for (int i = 0; i < n; i++) { int maxY = 0, dex = 0; for (int j = 0; j < m; j++) { if (!vis[j] && price[i] >= X[j]) { if (Y[j] > maxY) { maxY = Y[j]; dex = j; } } } if (maxY) vis[dex] = 1; ans += price[i] - maxY; } cout << ans << endl; return 0; }