Problem:
Score : 100 points

Problem Statement

We have A apples and P pieces of apple.

We can cut an apple into three pieces of apple, and make one apple pie by simmering two pieces of apple in a pan.

Find the maximum number of apple pies we can make with what we have now.

Constraints

All values in input are integers.

0 \leq A, P \leq 100

Input

Input is given from Standard Input in the following format:

A P

Output

Print the maximum number of apple pies we can make with what we have.

Sample Input 1

1 3

Sample Output 1

3

We can first make one apple pie by simmering two of the three pieces of apple. Then, we can make two more by simmering the remaining piece and three more pieces obtained by cutting the whole apple.

Sample Input 2

0 1

Sample Output 2

0

We cannot make an apple pie in this case, unfortunately.

Sample Input 3

32 21

Sample Output 3

58

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>

void inp_str(int*);

int main(void) {

    char str1[16];
    char str2[16];
    scanf("%s %s", str1, str2);

int A,P;

A=atoi(str1);
P=atoi(str2);

//printf("N=%d\n",N);
//printf("M=%d\n",M);

int ans;

ans=A*3+P;
ans=ans/2;

printf("%d\n",ans);


    return 0;

}


void inp_str(int instr[]){
char *ptr;
int z,i,count;
char str[100]={'\0'};
char *ln;

fgets(str, 100, stdin); // 入力："123456\n"
ln = strchr(str, '\n'); /* 改行文字を検索 */
if (ln != NULL) { /* 改行が読み取られていたかどうか */
   *ln = '\0';    /* 改行文字を終端文字に置き換える */
}
else {            /* 入力ストリーム上に文字が残ってる場合 */
   while (1) {    /* 改行文字が読み取られるまで空読みする */
       z = getchar();
      if (z == '\n' || z == EOF) break;
   }
}
	count=0;
    ptr = strtok(str, " ");
    i = atoi(ptr);
    instr[count]=i;
    count=count+1;
    // 2回目以降
    while(ptr != NULL) {
        // strtok関数により変更されたNULLのポインタが先頭
        ptr = strtok(NULL, " ");
        // ptrがNULLの場合エラーが発生するので対処
        if(ptr != NULL) {
		    i = atoi(ptr);
    instr[count]=i;
    		count=count+1;
        }
    }
}