compare numbers behaves strange...

Hi

I have a file with numbers in it. My program reads the values and
compare them and depending on the value I increment a counter. what I
have seen is that the evaluation fails. This is an extract of my
numbers:

7
7
7
34
92
111
294
121
142

This is parts of my program that checks the value (ms) read from the
file and increments the counters

      if( ms == 18) t18++;
      if( ms == 19) t19++;
      if( ms >= 20 && ms < 30)
      {
         print ms;
         t20++;
      }
      if( ms >= 30 && ms < 40) t30++;
      if( ms >= 40 && ms < 50) t40++;
      if( ms >= 50 && ms < 60) t50++;
      if( ms >= 60 && ms < 70) t60++;

As you can see I dont have any numbers between 20 and 30 but I still
get an increment for the t20 counter. When I print the value it is
"294". Why do I have this behaviour?