Why we require to intialize MaxhourglassSum=(-63) in the given solution of a problem?

Problem :- LINK

Input Format

Each of the lines of inputs 6 contains 6 space-separated integers .

Constraints

• -9<=a[i][j]<=9
• 0<=i,j<6

Output Format

Print the largest (maximum) hourglass{see link} sum found in .

#include<stdio.h>
int MaxhourglassSum=(-63);

void hourglass(int a[6][6],int i,int j){
            int sum=0;
            for(int m=i;m<i+3;m++){
                for(int n=j;n<j+3;n++){
                    if((m==i+1 && n==j) || (m==i+1 && n==j+2))
                    continue;
                    else
                    sum+=a[m][n];
                }
            }
            if(sum>MaxhourglassSum)
            MaxhourglassSum =sum;
}
int main(){
    int a[6][6];
        for(int i=0;i<6;i++){
            for(int j=0;j<6;j++){
                scanf("%d",&a[i][j]);
            }
        }

        for(int i=0;i<4;i++){
            for(int j=0;j<4;j++){
                    hourglass(a,i,j);
            }
        }

        printf("%d",MaxhourglassSum);

    return 0;
}