proc printf(formatstr: cstring){.header: "<stdio.h>", varargs.}
proc scanf(formatstr: cstring){.header: "<stdio.h>", varargs.}

var s : array[20,char]
for i in 0..999:
  printf("%03d\n",i)
  scanf("%s\n",addr s)
  if s[0] == 'u': break