/in/foo.cc:1:17: warning: extra tokens at end of #include directive
 #include<cstdio>{int a,b;scanf("%d %d",&a,&b);printf("%d\n",a+b);}
                 ^
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status