C语言全WA，求助

代码如下

#include <stdio.h>
#include <string.h>

int main(){
    char list[50][20010];
    int a=0, aLen=0, b=0, bLen=0, c, cLen=0, flag=0, n;
    int i, j;
    scanf("%d", &n);
    for(i=0;i<n;i++){
        getchar();
        getchar();
        gets(list[i]);
    }
    for(i=0;i<n;i++){
        if(list[i][0] >= 'a'){
            flag = list[i][0]-'a';
            j=2;
        }
        else{
            j=0;
        }
        a = b = aLen = bLen = cLen = 0;
        for(;list[i][j]!=' ';j++){
            a *= 10;
            a += list[i][j] - '0';
            aLen++;
        }
        j++;
        for(;list[i][j]!='\0';j++){
            b *= 10;
            b += list[i][j] - '0';
            bLen++;
        }
        switch(flag){
            case 0:
                c = a+b;
                printf("%d+%d=%d\n", a, b, c);

            break;
            case 1:
                c = a-b;
                printf("%d-%d=%d\n", a, b, c);
            break;
            case 2:
                c = a*b;
                printf("%d*%d=%d\n", a, b, c);
            break;
        }
        if(c < 0)
            cLen++;
        do{
            c /= 10;
            cLen++;
        }while(c);
        printf("%d\n", aLen+bLen+cLen+2);
    }
    return 0;
}