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#include <iostream>
#include <cmath>
 
 
 
int main() {
	int x;
	cin >> x;
	cout << (x==0? 1: int (log10 (x) + 1));
	return 0;
}

prog.cpp: In function 'int main()':
prog.cpp:8:2: error: 'cin' was not declared in this scope
  cin >> x;
  ^
prog.cpp:8:2: note: suggested alternative:
In file included from prog.cpp:1:0:
/usr/include/c++/5/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^
prog.cpp:9:2: error: 'cout' was not declared in this scope
  cout << (x==0? 1: int (log10 (x) + 1));
  ^
prog.cpp:9:2: note: suggested alternative:
In file included from prog.cpp:1:0:
/usr/include/c++/5/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^

Standard output is empty