хрень какая-то

#include <iostream>
#include <string>
#include <vector>
using namespace std;
int n, m,l;
vector<vector<int>>matrix(20,vector<int>(20,-1));
vector<vector<int>>A(20,vector<int>(20,-1));
int f(int i, int j){
    if (i == 0|| j == 0){
        return n;
    }

    return f(A[i][j-1],A[i-1][j]);
}
int main() {
    int d,b,a,i,j,g,g1;
    cin>>a>>b;
    for (i=0; i < a; ++i){
        for (j = 0;j <b; ++j){
            cin>>A[i][j];
        }
    }
    cout<< f(A[a-1][b-1],A[a-1][b-1]);
    cout<<"\n";
    return 0;
}