roads.cpp:6:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
6 | main()
| ^~~~
roads.cpp: In function 'int main()':
roads.cpp:23:14: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
23 | for(i=1;i<v.size();i++)
| ~^~~~~~~~~
roads.cpp:8:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
8 | for(scanf("%lld", &n);i++<n;)
| ~~~~~^~~~~~~~~~~~
roads.cpp:10:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
10 | scanf("%lld %lld %lld %lld", &a, &b, &c, &d);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~