http://codeforces.com/contest/69
A
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define pb push_back 7 #define eb emplace_back 8 #define maxn 1000006 9 #define rep(k,i,j) for(int k=i;k<j;k++) 10 typedef long long ll; 11 typedef unsigned long long ull; 12 13 int n; 14 struct sair{ 15 int x,y,z; 16 }a[105]; 17 18 int main(){ 19 #ifndef ONLINE_JUDGE 20 // freopen("input.txt","r",stdin); 21 #endif 22 std::ios::sync_with_stdio(false); 23 cin>>n; 24 for(int i=1;i<=n;i++){ 25 cin>>a[i].x>>a[i].y>>a[i].z; 26 } 27 int aa=0,bb=0,cc=0; 28 for(int i=1;i<=n;i++){ 29 aa+=a[i].x; 30 bb+=a[i].y; 31 cc+=a[i].z; 32 } 33 if(aa||bb||cc) cout<<"NO"<<endl; 34 else cout<<"YES"<<endl; 35 }