#include <iostream>
#include <vector>
using namespace std;

template <typename T>
ostream & operator<<(ostream & os, std::vector<T> v) {
	for(const T &x : v) {
		os << x << ' ';
	}
	return os << std::endl;
}

void replacee(vector<vector<char>> &vec, char oldd, char neww) {
    for(vector<char> &v:vec)
    {
        for(char &c:v) 
			if (c == oldd) {
				c = neww;
			}
    }
}

int main() {
	std::vector<std::vector<char>> v(5, std::vector<char>(5, 'o'));
	v.at(2).at(2) = 'x';
	std::cout << "Vector before:\n " << v << std::endl;
	replacee(v, 'o', 'I');
	std::cout << "Vector after:\n " << v << std::endl;
	
	return 0;
}