Language: C++

#include "bits/stdc++.h"
#include "ext/pb_ds/assoc_container.hpp"
#include "ext/pb_ds/tree_policy.hpp"
#define ordered_set tree<pair<int,int>, null_type,less<pair<int,int>>, rb_tree_tag,tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
#define int long long int
#define pb push_back
#define vec vector<int>
#define fo(i, n) for (int i = 0; i < n; i++)
#define foo(i, a, b) for (int i = a; i < b; i++)
#define mp make_pair
#define deb(x) cout << #x << " --> " << x << endl;
#define deb1a(v) cout << #v << "--->" << endl; for (auto it : v)  cout << it << " "; cout << endl;
#define deb2a(v) cout << #v << "--->" << endl;for (auto it:v){for(auto it1 : it){cout << it1 << " ";}cout<< endl;}
#define deb3a(v) cout << #v << "-->" << endl; for(auto it:v){cout << it.fi << " " << it.se << endl;}
#define mod 1000000007
#define so(v) sort(v.begin(),v.end())
#define fi first
#define se second
#define db1(x) cout<<#x<<"="<<x<<endl
#define db2(x,y) cout<<#x<<"="<<x<<","<<#y<<"="<<y<<endl
#define db3(x,y,z) cout<<#x<<"="<<x<<","<<#y<<"="<<y<<","<<#z<<"="<<z<<endl
int power(int x, unsigned int y, int p){ int res = 1;x = x % p;while (y > 0)  { if (y & 1)res = (res*x) % p;y = y>>1;  x = (x*x)% p;} return res;}
int mI(int a, int m)  {return power(a, m - 2, m);}
vector<vector<int>> dir = {{0, 1}, {0, -1}, {1, 0}, {-1, 0},{1,1},{1,-1},{-1,1},{-1,-1}};



void solve(){
    int n, m, k;
    cin >> n >> m >> k;
    vec a(n), b(n);
    int ans = 0;
    fo(i,n){
        cin >> a[i];
    }
    fo(i,m){
        cin >> b[i];
    }
    foo(i,1,n){
        a[i] += a[i - 1];
    }
    foo(i,1,m){
        b[i] += b[i - 1];
    }
    fo(i,n){
        auto it = upper_bound(b.begin(), b.end(), k) - b.begin();
        {
            ans = max(ans,it);
        }
        if(a[i]>k){
            break;
        }
        it = upper_bound(b.begin(), b.end(), k - a[i]) - b.begin();
        {
            ans = max(ans, i + 1+ it);
        }
        
    }
    cout << ans;
}
int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t=1;
    //cin >> t;
    
    while(t--){
        solve();
    }
}

Compiler output:
a.cc: In function 'void solve()':
a.cc:50:22: error: no matching function for call to 'max(long long int&, long int&)'
   50 |             ans = max(ans,it);
      |                   ~~~^~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:50:22: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'long int')
   50 |             ans = max(ans,it);
      |                   ~~~^~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:50:22: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   50 |             ans = max(ans,it);
      |                   ~~~^~~~~~~~