#include <bits/stdc++.h>   using namespace std;   const int maxn = 300005;   int f[maxn], n;   struct struc {     long long a[maxn];     int go[19][maxn], nxt[maxn];     void build(int ty = 0) {       if (!ty) {         for (int i = 1; i <= n; i++) scanf( %lld , &a[i]);         for (int i = n; i; i--) a[i] += a[i + 1];       }       static map<long long, int> pos;       pos.clear();       pos[0] = n + 1;       for (int i = n; i; i--) nxt[i] = pos[a[i]], pos[a[i]] = i;     }   } sav[3];   vector<pair<int, int> > up[maxn], dow[maxn];   int c[maxn];   void push(int i, int j, int v) {     c[max(i, j)] = max(c[max(i, j)], v);     if (i <= j) up[i].push_back(pair<int, int>(j, v));     if (j <= i) dow[j].push_back(pair<int, int>(i, v));   }   void trans(int i, int j, int v) {     push(i + 1, j, v), push(i, j + 1, v);     if (sav[0].nxt[i]) push(sav[0].nxt[i], j, v + 1);     if (sav[1].nxt[j]) push(i, sav[1].nxt[j], v + 1);     if (i == j && sav[2].nxt[i]) push(sav[2].nxt[i], sav[2].nxt[i], v + 1);   }   int main() {     scanf( %d , &n);     sav[0].build(), sav[1].build();     for (int i = 1; i <= n; i++) sav[2].a[i] = sav[0].a[i] + sav[1].a[i];     sav[2].build(1);     for (int i = 1; i <= n; i++) {       int go_up = (1 << 30), go_dow = (1 << 30);       trans(i, i, c[i]);       for (auto p : up[i])         if (p.second == c[i] + 1) go_dow = min(go_dow, p.first);       for (auto p : dow[i])         if (p.second == c[i] + 1) go_up = min(go_up, p.first);       if (go_up <= n + 1) trans(go_up, i, c[i] + 1);       if (go_dow <= n + 1) trans(i, go_dow, c[i] + 1);     }     printf( %d n , c[n + 1]);     return 0;   }   