C++ finding positions of regex in string

#include <iostream>
#include <string>
#include <regex>

int main()
{
	std::vector<int> mval;

	int closed_val = 0;
	int open_val = 0;
    std::string dup_line = "} } }";
    std::smatch m;
    std::regex_search(dup_line, m, std::regex("([\\}]+)"));
    for (auto mv : m) std::cout << mv << std::endl;
    std::cout << m.size() << std::endl;
	closed_val = dup_line.find(m[0]);
	mval.push_back(closed_val);
	try {
		if (m.size() >= 1) {
			for (int j = 1; j < m.size(); j++) {
                std::cout << dup_line << std::endl;
				dup_line = dup_line.substr(dup_line.find(m[j]) + 1, dup_line.size() - 1);
                std::regex_search(dup_line, m, std::regex("([}]+)"));
                std::cout << dup_line << std::endl;
				int f = dup_line.find(m[j]);
				if (f == -1 || f > dup_line.size() - 1)
					continue;
                    std::cout << f << std::endl;
                for (auto mv : m) std::cout << mv << std::endl;
				std::cout << dup_line.find(m[j + 1]) << std::endl;
				open_val = closed_val + (dup_line.find(m[j + 1]) == -1 ? 0 : dup_line.find(m[j + 1]));
				mval.push_back(open_val);
				closed_val = open_val;
			}
		}
	}
	catch (std::exception& error) {
		std::cerr << "error : " << error.what() << std::endl;
	}

    for (auto mv : mval) std::cout << mv << ":";
    std::cout << std::endl;
}

Compiler stderr
<source>: In function 'int main()':
<source>:20:75: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::match_results<__gnu_cxx::__normal_iterator<const char*, std::__cxx11::basic_string<char> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |                                                         for (int j = 1; j < m.size(); j++) {
      |                                                                         ~~^~~~~~~~~~
<source>:26:82: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |                                                                 if (f == -1 || f > dup_line.size() - 1)
      |                                                                                ~~^~~~~~~~~~~~~~~~~~~~~
<source>:31:114: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   31 |                                                                 open_val = closed_val + (dup_line.find(m[j + 1]) == -1 ? 0 : dup_line.find(m[j + 1]));
      |       

Program returned: 0
Program stdout
}
}
2
} } }
 } }
1
}
}
0
0:0: