bank.cpp:69:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^
bank.cpp: In function 'int main()':
bank.cpp:75:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for(int i = 0; i < m; i++)
  ^~~
bank.cpp:77:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   calc(0);
   ^~~~
bank.cpp:71:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~~
bank.cpp:73:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i]);
   ~~~~~^~~~~~~~~~~~~
bank.cpp:76:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &b[i]);
   ~~~~~^~~~~~~~~~~~~