Activity selection problem

#1

#include<bits/stdc++.h>
using namespace std;

bool compare( int a,int b)
{
return a<b;
}
void max_activity(int m[],int n[],int N)
{
int i=0;
cout<<i;

for(int j=1;j<N;j++)
{
	if(m[j]>n[i])
	{
		cout<<j;
		i=j;
	}
}

}
int main() {
int m[];
int n[];

int N = sizeof(m)/sizeof(int);
N = sizeof(n)/sizeof(int);

for(int i=0;i<N;i++)
{
cin>>m[i]>>n[i];
}
max_activity(m,n,N,compare);
return 0;
}
This is the code ,but it is having a compilation error as storage size of m and n are not given. Help me resolving

#2

@ankita_10 please provide your code in coding blocks IDE.

#3

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