int main() { 1; // decimal 2_1; 2_147_483_647; 37LL; 45ull; 89llu; 99LLu; 56_lu; 88_LLu; // 0; // octal 0u; 0_3_77; 0_377_ul; 0x1; // hexadecimal 0x1u; 0xabL; 0x_80000000; 0x_fff; 0x_ef3d_aa5c; 0x_3LL; 3.; // integral real 3_100.; 1_000_000.; 3.1; // integral/fractional real 3.141_592_654L; 123_456.123_456; 3E1; // integral/exponent real 3_e1f; 3_E1_1_F; 3_E_11; 3_e_+11; 3_E_-11; 3.0E1; // integral/fractional/exponent real 3.0_E1L; 3.0_e1_1; 3.0_E_11_l; 3.0_e_+11l; 3.0_E_-11; 123_456.123_456E-16; 0x_ff.ffp0; // hex real 0x_1.ffff_ffff_p_128_l; }