Reason Why this Happens in c

Question

i am using gcc and i have written this code and intentionally loop is written wrong

int main() {
  int a[3][3];
  int i=0;
  int j=0;
  int num=0;
  for(i=0;i<4;i++) {
    for(j=0;j<4;j++) {
      a[i][j]=0;
    }
  }
  for(i=0;i<2;i++)
    for(j=0;j<2;j++)
      printf("%d",a[i][j]);
  return 0;
}

when I do a[i][j]=0; or a[i][j]=1; it goes to infinite loop but when I enter other than 0 or 1 it executes correctly.

Can anybody tell me why this happens?