gas.cpp: In function 'int main()':
gas.cpp:12:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &city);
     ~~~~~^~~~~~~~~~~~~
gas.cpp:15:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &dist[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~
gas.cpp:19:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &gas[i]);
         ~~~~~^~~~~~~~~~~~~~~~~