#include <iostream>
#include <string>
 
int main()
 
{
    std::string str = "asdfgsdfg:ijtij ijdfgh ija::saf 1999 bp";
    int start = str.find(":");
    int end = str.find("bp", start);
    std::string substring;
    if (start != std::string::npos && end != std::string::npos)
    {
       substring = str.substr(start + 1, end - start - 1);
    }
    else
    {
       // Whatever you want to do if the markers are missing.
    }
    std::cout << substring;
}

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