using namespace std;
#include <iostream>
int main(int argc, char *argv[])
{
  FILE *in_file, *out_file;
  if( argc < 3)  {
    printf("The programs has the following structure :\n");
    printf("write in the name of the input and output files \n");
    exit(0);
  }
  in_file = fopen( argv[1], "r");// returns pointer to the  input file
  if( in_file == NULL )  { // NULL means that the file is missing
    printf("Can't find the input file %s\n", argv[1]);
    exit(0);