Your task is to take an input, for example:
And produce an output, which per this example is
a,b,4,5 means: the lowercase character "a" is repeated 4 times, and is then followed by the lowercase character "b" repeated 5 times, making the total number of characters 4+5=9
Another example: the input
a,B,5,4, should produce the output
aaaaaBBBB, which is: the lowercase letter "a" is repeated 5 times, followed by the uppercase letter "B" repeated 4 times.
Some more examples:
Input --> Output a,b,4,6 --> aaaabbbbbb a,b,c,1,2,3 --> abbccc a,e,d,f,g,1,2,3,4,5 --> aeedddffffggggg A,b,4,5 --> AAAAbbbbb A,b,C,1,2,3 --> AbbCCC A,B,c,D,1,2,3,4 --> ABBcccDDDD
Note how the output must have only the required letters, nothing else, except trailing newlines.
The format of the input should be exactly as you see in the above examples, so your code does not have to support any additional formats/styles of the input.
The output must be displayed in a format exactly as the examples show, this means no commas, spaces, etc, separating the letters. Trailing newlines are okay, if you cannot avoid them.
Standard loopholes are disallowed, and the output is case sensitive.
This is code-golf, so the shortest code in bytes wins!