Hi, I have a ASCII text file whose entries look like this 111 AA 25 XX 111 AB -5 XX 222 AC 25 XX 222 AD 20 XX 222 AE 21 XX 333 AF 88 XX 444 AG 21 XX 444 AH 90 XX and so on..... In this file the first column represents a unique number refering to an experiment. Any particular experiment was repeated a random number of times, such as experiment 111 was repeated twice, experiment 222 was repeated 3 times, experiment 333 was done only once. I need to know how many unique experiments were done. To clarify it further, in above example 4 experiments (111, 222, 333 and 444) were done. I need to know this in a file which has 1300 rows. Please help.