#include #include char rot13(char x) { if ('a' <= x && x <= 'z') return ((x - 'a') + 13) % 26 + 'a'; if ('A' <= x && x <= 'Z') return ((x - 'A') + 13) % 26 + 'A'; return x; } #define BUFFER_SIZE (640 * 1000) char buffer[BUFFER_SIZE]; int main(void) { while (!feof(stdin)) { size_t n = fread(buffer, sizeof(buffer[0]), BUFFER_SIZE, stdin); for (size_t i = 0; i < n; ++i) { buffer[i] = rot13(buffer[i]); } fwrite(buffer, sizeof(buffer[0]), n, stdout); } return 0; }