bzoj1108[POI2007]天然气管道Gaz

刷完神题来水题。。
所以说这种题目的意义何在www

#include<cstdio>#include<algorithm>#include<cstring>#include<iostream>#define fo(i,a,b) for(int i=a;i<=b;i++)#define fd(i,a,b) for(int i=a;i>=b;i--)typedef long long ll;int n;ll ans;int main() {    scanf("%d",&n);    fo(i,1,n)    {        int x,y;        scanf("%d%d",&x,&y);        ans+=y-x;    }   fo(i,1,n)    {        int x,y;        scanf("%d%d",&x,&y);        ans+=x-y;    }    printf("%lld\n",ans);    return 0;}