#include <stdio.h>

int xy_to_num(int x, int y, char *fname)
{
  FILE *fp ;
  char s[80] ;
  int width, height, run_length, reg_num, pos, i ;

  fp = fopen(fname, "r") ;
  fgets(s, 80, fp) ;
  sscanf(s, "%d %d", &width, &height) ;
  pos = y*width + x ;
  i = 0 ;
  do {
    fgets(s, 80, fp) ;
    sscanf(s, "%d %d", &run_length, &reg_num) ;
    i += run_length ;
  } while (i <= pos) ;
  close(fp) ;
  return(reg_num) ;
}