undefined reference to `WinMain@16' : Mingw error while compiling

Question

This is the problem code. Please help!!

#include<stdio.h>

int mainn()
{
     printf("Hello World");
     return 0;
}

Tried fixing from yt videos but they suggest to save the file before execution. I did but it keeps failing.

c:/mingw/bin/../lib/gcc/mingw32/6.3.0/../../../libmingw32.a(main.o):(.text.startup+0xa0): undefined reference to `WinMain@16'
collect2.exe: error: ld returned 1 exit status

This is what the terminal shows me.