Below is my input file:

* 1st column is combination of Hour of day and Minute
* 2nd column is count

the data is minute wise.

I need to convert the data into minute wise by summing on each block of minutes, i.e [1-5, 6-10 and so on]. I need this data to plot in jfree chart. Please suggest how get the output

Input:

```
11.01:5
11.02:4
11.03:3
11.04:8
11.05:2
12.11:3
12.12:4
12.13:1
12.15:0
13.03:04
22.56:01
22.57:03
22.58:2
23.00:0

```

Output:

```
11.05:22
12.15:8
13.05:4
23.00:6

```