Harris-Benedict等式

else if在这里有什么错误，不就是分两种情况吗，男女两种，为什么无法执行

#include <stdio.h>
int main()
{
  int weight,height,age;
  float MBMR,FBMR,amount;
  char M,F,sex;
    scanf("%d %d %d %c",&height,&weight,&age,&sex);

  FBMR=655+(4.3*weight*2.2)+(4.7*height*0.39)-(4.7*age);
  MBMR=66+(6.3*weight*2.2)+(12.9*height*0.39)-(6.8*age);
  if(sex=='F'){
  amount=FBMR/230.0;
  printf("您需要消耗%.2f块巧克力\n",amount);
  }else  if(sex=='M')
  amount=MBMR/230.0;
  printf("您需要消耗%.2f块巧克力\n",amount);
  return 0;
}