为什么这个RE了

#include<bits/stdc++.h>
using namespace std;
class Dm
{
    public:
        long long gs, bg[100005][100005], cs, lx, guz, gez, dx, i;
        void sr()
        {
            cin >> gs >> cs;
        }
        void cz1()
        {
            bg[guz][gez] = dx;
            cout << bg[guz][gez] << endl; 
        }
        void cz2()
        {
            cout << bg[guz][gez] << endl;
        }
        void zt()
        {
            for(i = 1; i <= cs; i++)
            {
                cin >> lx >> guz >> gez;
                if(lx == 1)
                {
                    cin >> dx;
                    cz1();
                }
                else cz2();
            }
        }
};
int main()
{
    Dm dm;
    dm.sr();
    dm.zt();
    return 0;
}