#include<stdio.h>
int main()
{
   int a,b;
   float c;
   scanf("%d%d",&a,&b);
   c=a*b*1.0/2;
   printf("%.1f",c);

    return 0;
}

#include <stdio.h>

int main() { int a = 0; int b = 0; float c = 0; input: printf("请输入两个整数,要求大于等于0而且小于等于100\n"); scanf("%d %d", &a, &b); if ((a >= 0 && a <= 100) && (b >= 0 && b <= 100)) { c = (a * b) / 2; printf("该直角三角形的面积是:%.1f\n", c); } else { printf("输入错误，请重新输入\n"); } goto input; return 0; }

#include <stdio.h> #include <iso646.h> int main (void) {int A,B; double F=0.5; double C; scanf("%d%d",&A,&B); C=ABF; if (C>=0 and C<=5000) printf("%.1f",C); return 0; }