A simple approach is to use sscanf, pass the string you read from cin to it as the first argument
sscanf(s, "(%d,%d,%d,%c)", &a, &b, &c))
If you want to parse the string from scratch, just focus the pattern.
In this case, the pattern is
'(', number, ',', number, ',', number, ',', char, ')'
So you can locate the three commas, then simply extract three numbers from between them.
A more complicated method is regex. But C++ doesn't have native support for that (the Boost library does)