how to parse line into number and string? [closed]

I would like to parse a sentence beginning with a number:

2 random sentece.
5 another one.
8 this is really long sentence.

Into int number holding the beginning number and the rest in std::string sentence. So in the first line, the parsing output will be number == 2 and sentence == "random sentence". The input is read from stdin, but the classical std::cin >> number >> sentence does'n work, since the parsing of string would end once it reaches a space. But I want to make the string beginning after the initial number to the end of line \n. So, how to do it in C++?