func_code_string: #include <bits/stdc++.h>   int main() {     int a[4], i, test, flag = 1, flag2 = 1;     double test2, testn;     for (i = 0; i < 4; i++) scanf( %d , &a[i]);     test = a[1] - a[0];     if (a[2] - a[1] == test && a[3] - a[2] == test) {       printf( %d , a[3] + test);       flag = 0;       flag2 = 0;     }     if (flag) {       test2 = (double)a[1] / a[0];       if (fabs((double)a[2] / a[1] - test2) < 0.001 &&           fabs((double)a[3] / a[2] - test2) < 0.001) {         testn = a[3] * test2;         if (fabs(testn - (int)testn) < 0.001) {           printf( %.0f , testn);           flag2 = 0;         }       }     }     if (flag2) printf( 42 );     return 0;   }   