11.20.2

#include<stdio.h>

int f(int x);

int main()

{

int x;

scanf("%d",&x);

printf("%d",f(x));

return 0;

}

int f(int x)

{int i,sum=10;

if(x>1){

for(i=x;i>1;i--)

{sum+=2;

}

}

return sum;

}