#include <string>
#include <algorithm>
#include <iostream>
using namespace std;


bool isDigit(const string& str)
{
    return all_of(str.begin(), str.end(), ::isdigit);
}


string getIntegerFromExpression(string str) {
    bool hasFloatingPoint = false, hasExp = false, hasDigit = false;
    string output;

    for (string::iterator it = str.begin(); it != str.end(); ++it) {
        const string tkn = string(1, *it);
        if (isDigit(tkn) || (tkn == "E" && !hasExp) || (tkn == "." && !hasFloatingPoint)) {
            if (tkn == "E") hasExp = true;
            if (tkn == ".") hasFloatingPoint = true;
            if (isDigit(tkn)) hasDigit = true;
            output += tkn;
        }
        else if (hasDigit) {
            break;
        }
    }
    if (hasDigit || hasExp) {
        return output;
    }
    return "";
}

int main() {



    string a = "4E53GGGH";
    string b = "3.4E53=B";
    cout << getIntegerFromExpression(a) << endl;
    cout << getIntegerFromExpression(b) << endl;

    system("pause");
    return 0;
}