Homework Checker

� Your younger brother has just finished his homework for the part "additions and subtractions for integers not greater than one hundred" and asks you to check the answers. Each question (together with the answer computed by your younger brother) is formatted either as a + b = c or a - b = c, where a and b are numbers prepared by the teacher (they are guaranteed to be non-negative integers not greater than 100), c is the answer computed by your younger brother and is either a non-negative integer not greater than 200, or a single character `?' (that means, he is unable to compute the answer).

Input 

There will be at most 100 lines in the input. Each line contains a question with your younger brother's answer, formatted as stated above. There will be no space characters in each line (excluding the newline character). Numbers will never have leading zeros.

Output 

Print a single integer in a line, the number of correct answers.

Sample Input 

1+2=3
3-1=5
6+7=?
99-0=99

Sample Output 

2

Problemsetter: Rujia Liu, Special Thanks: Yiming Li

#include <stdio.h>

int main() {
    char cmd[50];
    int a, b, c, ans = 0;
    while(gets(cmd)) {
        if(sscanf(cmd, "%d+%d=%d", &a, &b, &c) == 3) {
            if(a+b == c)
                ans++;
        }
        if(sscanf(cmd, "%d-%d=%d", &a, &b, &c) == 3) {
            if(a-b == c)
                ans++;
        }
    }
    printf("%d\n", ans);
    return 0;
}

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