Language: C++


#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
%:pragma GCC optimize("Ofast")
%:pragma GCC optimize("inline")
%:pragma GCC optimize("-fgcse")
%:pragma GCC optimize("-fgcse-lm")
%:pragma GCC optimize("-fipa-sra")
%:pragma GCC optimize("-ftree-pre")
%:pragma GCC optimize("-ftree-vrp")
%:pragma GCC optimize("-fpeephole2")
%:pragma GCC optimize("-ffast-math")
%:pragma GCC optimize("-fsched-spec")
%:pragma GCC optimize("unroll-loops")
%:pragma GCC optimize("-falign-jumps")
%:pragma GCC optimize("-falign-loops")
%:pragma GCC optimize("-falign-labels")
%:pragma GCC optimize("-fdevirtualize")
%:pragma GCC optimize("-fcaller-saves")
%:pragma GCC optimize("-fcrossjumping")
%:pragma GCC optimize("-fthread-jumps")
%:pragma GCC optimize("-funroll-loops")
%:pragma GCC optimize("-fwhole-program")
%:pragma GCC optimize("-freorder-blocks")
%:pragma GCC optimize("-fschedule-insns")
%:pragma GCC optimize("inline-functions")
%:pragma GCC optimize("-ftree-tail-merge")
%:pragma GCC optimize("-fschedule-insns2")
%:pragma GCC optimize("-fstrict-aliasing")
%:pragma GCC optimize("-fstrict-overflow")
%:pragma GCC optimize("-falign-functions")
%:pragma GCC optimize("-fcse-skip-blocks")
%:pragma GCC optimize("-fcse-follow-jumps")
%:pragma GCC optimize("-fsched-interblock")
%:pragma GCC optimize("-fpartial-inlining")
%:pragma GCC optimize("no-stack-protector")
%:pragma GCC optimize("-freorder-functions")
%:pragma GCC optimize("-findirect-inlining")
%:pragma GCC optimize("-fhoist-adjacent-loads")
%:pragma GCC optimize("-frerun-cse-after-loop")
%:pragma GCC optimize("inline-small-functions")
%:pragma GCC optimize("-finline-small-functions")
%:pragma GCC optimize("-ftree-switch-conversion")
%:pragma GCC optimize("-foptimize-sibling-calls")
%:pragma GCC optimize("-fexpensive-optimizations")
%:pragma GCC optimize("-funsafe-loop-optimizations")
%:pragma GCC optimize("inline-functions-called-once")
%:pragma GCC optimize("-fdelete-null-pointer-checks")#pragma GCC optimize("Ofast",3,"inline")
#include <bits/stdc++.h>
using namespace std;
int n;
string s;
string str1,str2;
int main(){
	ios_base::sync_with_stdio(false);
	cin>>n>>s;
	for(int i=n/2;i>0;i--){
		for(int k=0;k<n-i*2+2;k++){
			str1=s.substr(k,i);
	//		str2
			for(int j=k+i;j<=n-i;j++){
				str2=s.substr(j,i);
				if(str2==str1){
					cout<<i;
					return 0;
				}
			}	
		}
			
	}
	cout<<0;
	return 0;
}
//string substr(int pos = 0,int n = npos)


Compiler output:
a.cc:49:54: error: stray '#' in program
   49 | %:pragma GCC optimize("-fdelete-null-pointer-checks")#pragma GCC optimize("Ofast",3,"inline")
      |                                                      ^
a.cc:24:40: warning: bad option '-fwhole-program' to pragma 'optimize' [-Wpragmas]
   24 | %:pragma GCC optimize("-fwhole-program")
      |                                        ^
a.cc:31:42: warning: bad option '-fstrict-overflow' to pragma 'optimize' [-Wpragmas]
   31 | %:pragma GCC optimize("-fstrict-overflow")
      |                                          ^
a.cc:33:42: warning: bad option '-fcse-skip-blocks' to pragma 'optimize' [-Wpragmas]
   33 | %:pragma GCC optimize("-fcse-skip-blocks")
      |                                          ^
a.cc:47:52: warning: bad option '-funsafe-loop-optimizations' to pragma 'optimize' [-Wpragmas]
   47 | %:pragma GCC optimize("-funsafe-loop-optimizations")
      |                                                    ^
a.cc:49:55: error: '#pragma GCC optimize' string is badly formed
   49 | %:pragma GCC optimize("-fdelete-null-pointer-checks")#pragma GCC optimize("Ofast",3,"inline")
      |                                                       ^~~~~~
a.cc:55:10: warning: bad option '-fwhole-program' to attribute 'optimize' [-Wattributes]
   55 | int main(){
      |          ^
a.cc:55:10: warning: bad option '-fstrict-overflow' to attribute 'optimize' [-Wattributes]
a.cc:55:10: warning: bad option '-fcse-skip-blocks' to attribute 'optimize' [-Wattributes]
a.cc:55:10: warning: bad option '-funsafe-loop-optimizations' to attribute 'optimize' [-Wattributes]