Language: C++

#include <stdio.h>
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <cstring>
#include <algorithm>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <ctime>
#include <vector>
#include <fstream>
#include <list>
#include <iomanip>
#include <numeric>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define ms(s) memset(s, 0, sizeof(s))
const int INF = 1e9;
inline int read(){
    int X = 0,w = 0 ;
    char ch = 0;
    while(!isdigit(ch)) {w |= ch == '-';ch = getchar();}
    while(isdigit(ch)) X = (X<<3) + (X<<1) + (ch ^ 48),ch = getchar();
    return w ? -X : X;
}

struct node
{
    int u,w;
};
vector<node> q[100005];
int vis[100005],tempvis[100005];
int flag;
void dfs(int cur,int pre)
{
    vis[cur]=1;
    if(flag) return;
    int len=q[cur].size();
    for(int i=0;i<len;i++)
    {
        int tmp=q[cur][i].u;
        if(!vis[tmp])
        {
            dfs(tmp,cur);
        }
        else if(pre!=tmp)
        {
            flag=1;
            return;
        }
    }
}
int tmpk,tmpw;
void dfs1(int cur,int cost)
{
    if(cost>tmpw)
    {
        tmpk=cur;
        tmpw=cost;
    }
    vis[cur]=1;
    tempvis[cur]=1;
    int i,len=q[cur].size();
    for(i=0;i<len;i++)
    {
        int t=q[cur][i].u;
        if(!tempvis[t])
        {
            dfs1(t,cost+q[cur][i].w);
        }
    }
}
int main()
{
    int 100005,m;
    cin>>100005>>m;
    for(int i=0;i<m;i++)
    {
        int x,y;
        cin>>x>>y;
        node tmp;
        w=1;
        tmp.u=x;tmp.w=1;
        q[y].push_back(tmp);
        tmp.u=y;
        q[x].push_back(tmp);

    }
    flag=0;
    memset(vis,0,sizeof(vis));
    for(int i=1;i<=100005;i++)
    {
        if(!vis[i])
            dfs(i,0);
    }
    int resw=0;
    memset(vis,0,sizeof(vis));
    for(int i=1;i<=100005;i++)
    {
        if(!vis[i])
        {
            tmpw=-1;
            memset(tempvis,0,sizeof(tempvis));
            dfs1(i,0);
            if(tmpw>resw)
            {
                resw=tmpw;
            }
            memset(tempvis,0,sizeof(tempvis));
            tmpw=-1;
            dfs1(tmpk,0);
            if(tmpw>resw)
            {
               resw=tmpw;
           }
        }
    }
    cout<<resw;
    return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:80:9: error: expected unqualified-id before numeric constant
   80 |     int 100005,m;
      |         ^~~~~~
a.cc:81:8: error: no match for 'operator>>' (operand types are 'std::istream' {aka 'std::basic_istream<char>'} and 'int')
   81 |     cin>>100005>>m;
      |     ~~~^~~~~~~~
      |     |    |
      |     |    int
      |     std::istream {aka std::basic_istream<char>}
In file included from /usr/include/c++/14/iostream:42,
                 from a.cc:2:
/usr/include/c++/14/istream:170:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  170 |       operator>>(bool& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:170:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'bool&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:174:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  174 |       operator>>(short& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:174:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: warning: overflow in conversion from 'int' to 'short int' changes value from '100005' to '-31067' [-Woverflow]
   81 |     cin>>100005>>m;
      |          ^~~~~~
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'short int&' to a value of type 'int'
/usr/include/c++/14/istream:177:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  177 |       operator>>(unsigned short& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:177:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: warning: unsigned conversion from 'int' to 'short unsigned int' changes value from '100005' to '34469' [-Woverflow]
   81 |     cin>>100005>>m;
      |          ^~~~~~
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'short unsigned int&' to a value of type 'int'
/usr/include/c++/14/istream:181:7: note: candidate: 'std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]' (near match)
  181 |       operator>>(int& __n);
      |       ^~~~~~~~
/usr/include/c++/14/istream:181:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'int&' to an rvalue of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:184:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  184 |       operator>>(unsigned int& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:184:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'unsigned int&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:188:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  188 |       operator>>(long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:188:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'long int&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:192:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  192 |       operator>>(unsigned long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:192:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'long unsigned int&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:199:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  199 |       operator>>(long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:199:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'long long int&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:203:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  203 |       operator>>(unsigned long long& __n)
      |       ^~~~~~~~
/usr/include/c++/14/istream:203:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'long long unsigned int&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:219:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  219 |       operator>>(float& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:219:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'float&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:223:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  223 |       operator>>(double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:223:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'double&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:227:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  227 |       operator>>(long double& __f)
      |       ^~~~~~~~
/usr/include/c++/14/istream:227:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: cannot bind non-const lvalue reference of type 'long double&' to a value of type 'int'
   81 |     cin>>100005>>m;
      |          ^~~~~~
/usr/include/c++/14/istream:328:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  328 |       operator>>(void*& __p)
      |       ^~~~~~~~
/usr/include/c++/14/istream:328:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: invalid conversion from 'int' to 'void*' [-fpermissive]
   81 |     cin>>100005>>m;
      |          ^~~~~~
      |          |
      |          int
a.cc:81:10: error: cannot bind rvalue '(void*)100005' to 'void*&'
/usr/include/c++/14/istream:122:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__istream_type& (*)(__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>]' (near match)
  122 |       operator>>(__istream_type& (*__pf)(__istream_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:122:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: invalid conversion from 'int' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&)' {aka 'std::basic_istream<char>& (*)(std::basic_istream<char>&)'} [-fpermissive]
   81 |     cin>>100005>>m;
      |          ^~~~~~
      |          |
      |          int
/usr/include/c++/14/istream:126:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(__ios_type& (*)(__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::basic_istream<char>; __ios_type = std::basic_ios<char>]' (near match)
  126 |       operator>>(__ios_type& (*__pf)(__ios_type&))
      |       ^~~~~~~~
/usr/include/c++/14/istream:126:7: note:   conversion of argument 1 would be ill-formed:
a.cc:81:10: error: invalid conversion from 'int' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&)' {aka 'std::basic_ios<char>& (*)(std::basic_ios<char>&)'} [-fpermissive]
   81 |     cin>>100005>>m;
      |          ^~~~~~
      |          |
      |          int
/usr/include/c++/14/istream:133:7: note: candidate: 'std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; __istream_type = std::