View Compilation Error

0_0_22174492_20931.c: In function 'main':
0_0_22174492_20931.c:1:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
 main(n){for(float s;~scanf("%d",&n);printf("%.5f\n",s))for(s=1;n-=2;)s+=s/~n;}
         ^
0_0_22174492_20931.c:1:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code