#include <unistd.h>
#include <string.h>

void unescape(char *p, char *s) {
        int i, l = strlen(p), m = strlen(s);
        for (i = 0; i < m; ++i)
                switch(s[i]) {
                case '\\':
                        p[l++] = '\\';
                        p[l++] = '\\';
                        break;
                case '\n':
                        p[l++] = '\\';
                        p[l++] = 'n';
                        break;
                case '"':
                        p[l++] = '\\';
                        p[l++] = '"';
                        break;
                default:
                        p[l++] = s[i];
                }
}

int main(int argc, char **argv) {
        char before[] = "#include <unistd.h>\n#include <string.h>\n\nvoid unescape(char *p, char *s) {\n        int i, l = strlen(p), m = strlen(s);\n        for (i = 0; i < m; ++i)\n                switch(s[i]) {\n                case '\\\\':\n                        p[l++] = '\\\\';\n                        p[l++] = '\\\\';\n                        break;\n                case '\\n':\n                        p[l++] = '\\\\';\n                        p[l++] = 'n';\n                        break;\n                case '\"':\n                        p[l++] = '\\\\';\n                        p[l++] = '\"';\n                        break;\n                default:\n                        p[l++] = s[i];\n                }\n}\n\nint main(int argc, char **argv) {\n        char before[] = \"";
        char s[] = "        char PROG[] = \"echo\";\n        char p[100000] = \"\";\n        char *nv[4] = {argv[0], p, argv[1], NULL};\n        strcat(p, before);\n        unescape(p, before);\n        strcat(p, \"\\\";\\n        char s[] = \\\"\");\n        unescape(p, s);\n        strcat(p, \"\\\";\\n\");\n        strcat(p, s);\n        execvp(PROG, nv);\n}\n";
        char PROG[] = "echo";
        char p[100000] = "";
        char *nv[4] = {argv[0], p, argv[1], NULL};
        strcat(p, before);
        unescape(p, before);
        strcat(p, "\";\n        char s[] = \"");
        unescape(p, s);
        strcat(p, "\";\n");
        strcat(p, s);
        execvp(PROG, nv);
}