#include <iostream>
#include <set>
#include <cstring>

using namespace std;

typedef struct 
{
   char grid[7];
} wrap;

bool compare(wrap w1, wrap w2)
{
   return strcmp(w1.grid, w2.grid) == -1;
}
set <wrap, bool(*)(wrap, wrap)> myset(compare);

int main() {
	wrap w1 { "abcdef" };
	wrap w2 { "ABCDEF" };
	myset.insert(w1);
	myset.insert(w2);
	std::cout << myset.begin()->grid[0] << '\n';
}