123.cpp:63:29: error: bits / stdc++.h : No such file or directory 123.cpp: In function 'int main()': 123.cpp:26: warning: unused variable 'k' 123.cpp: At global scope: 123.cpp:72: error: '::main' must return 'int' 123.cpp: In function 'int main()': 123.cpp:72: error: redefinition of 'int main()' 123.cpp:22: error: 'int main()' previously defined here