#include <bits/stdc++.h> using namespace std; const int MAXN = 200005; using lint = long long; using pi = pair<int, int>; int n; int cnt[2][MAXN]; int main(){ scanf("%d",&n); lint dap = 0; for(int i=0; i<n*2; i++){ int x, y; scanf("%d %d",&x,&y); if(x < 1){ dap += 1 - x; x = 1; } if(x > n){ dap += x - n; x = n; } if(y < 1){ dap += 1 - y; y = 1; } if(y > 2){ dap += y - 2; y = 2; } cnt[y-1][x]++; } for(int i=1; i<=n; i++){ // free flow cnt[0][i]--; cnt[1][i]--; // cost 1 flow which I never have to negate if(1ll * cnt[0][i] * cnt[1][i] < 0){ if(cnt[0][i] < 0){ int delt = min(-cnt[0][i], cnt[1][i]); dap += delt; cnt[0][i] += delt; cnt[1][i] -= delt; } else{ int delt = min(-cnt[1][i], cnt[0][i]); dap += delt; cnt[0][i] -= delt; cnt[1][i] += delt; } } // abandon center edge, and proceed recursively dap += abs(cnt[0][i]) + abs(cnt[1][i]); cnt[0][i+1] += cnt[0][i]; cnt[1][i+1] += cnt[1][i]; } cout << dap << endl; }

joi2019_ho_t4.cpp: In function 'int main()':
joi2019_ho_t4.cpp:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
joi2019_ho_t4.cpp:14:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   int x, y; scanf("%d %d",&x,&y);
             ~~~~~^~~~~~~~~~~~~~~